本文为新手以及有经验的专业人士提供了一个C++编程面试问题列表。这些问题旨在测试候选者对以下主题的理解：

• C++语法及语义
• 数据结构和算法
• 面向对象编程
• 内存管理
• 指针
• 模板

1. 编写程序判断数字是正数还是负数

// C++ Program to check whether a number is positive or 
// negative 
#include <iostream> 
using namespace std; int main() 
{ int number; number = -100; if (number >= 0) { cout << number << " is a positive number." << endl; } else { cout << number << " is a negative number." << endl; } return 0; 
}

输出：

-100 is a negative number.

2. 编写程序找出三个数中最大的一个

// C++ program to find greatest 
// among three numbers using 
#include <iostream> 
using namespace std; int main() 
{ int a = 10, b = 20, c = 30; cout << "The Greatest Among Three Numbers is : "; if (a >= b && a >= c) { cout << a << endl; } else if (b >= a && b >= c) { cout << b << endl; } else { cout << c << endl; } return 0; 
}

输出：

The Greatest Among Three Numbers is : 30

3. 编写程序检查数字是偶数还是奇数

// C++ program to check 
// for even or odd 
#include <iostream> 
using namespace std; // Returns true if n is 
// even, else odd 
bool isEven(int n) { return (n % 2 == 0); } // Driver code 
int main() 
{ int n = 247; if (isEven(n) == true) { cout << "Even" << endl; } else { cout << "Odd"; } return 0; 
}

输出：

Odd

4. 编写程序计算字符的ASCII值

// C++ Program to find ASCII value of a character 
#include <iostream> 
using namespace std; int main() 
{ char ch; ch = 'A'; cout << "The ASCII value of " << ch << " is " << int(ch) << endl; return 0; 
}

输出：

The ASCII value of A is 65

5. 编写程序检查字符是元音还是辅音

// C++ Program to print whether a character is vowel or not 
#include <cctype> 
#include <iostream> 
using namespace std; int main() 
{ char ch = 'e'; if (isalpha(ch)) { if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o'|| ch == 'u' || ch == 'A' || ch == 'E'|| ch == 'I' || ch == 'O' || ch == 'U') { cout << ch << " is a vowel." << endl; } else { cout << ch << " is a consonant." << endl; } } else { cout << ch << " is not an alphabet." << endl; } return 0; 
}

输出：

e is a vowel.

6. 编写程序检查一个字符是否为字母表

// C++ program to print whether a character is an alphabet 
// or not 
#include <cctype> 
#include <iostream> 
using namespace std; int main() 
{ char ch; ch = 'a'; if (isalpha(ch)) { cout << ch << " is an alphabet." << endl; } else { cout << ch << " is not an alphabet." << endl; } return 0; 
}

输出：

a is an alphabet.

7. 编写程序，在不使用 strlen()函数的情况下计算字符串的长度

// C++ Program to find the length of a string without using 
// strlen() 
#include <cstring> 
#include <iostream> 
using namespace std; int main() 
{ string str = "GeeksforGeeks"; int length = 0; for (int i = 0; str[i] != '\0'; i++) { length++; } cout << "The length of the string is: " << length << endl; return 0; 
}

输出：

The length of the string is: 13

8. 编写程序来切换字符串中的每个字符

// C++ Program to toggle string 
#include <cstring> 
#include <iostream> 
using namespace std; int main() 
{ string str = "GeeksforGeeks"; for (int i = 0; str[i] != '\0'; i++) { if (islower(str[i])) { str[i] = toupper(str[i]); } else if (isupper(str[i])) { str[i] = tolower(str[i]); } } cout << "Toggled string: " << str << endl; return 0; 
}

输出：

Toggled string: gEEKSFORgEEKS

9. 编写程序来统计元音的数量

// C++ Program to count the number of vowels 
#include <cstring> 
#include <iostream> 
using namespace std; int main() 
{ string str = "GeeksforGeeks to the moon"; int vowels = 0; for (int i = 0; str[i] != '\0'; i++) { if (str[i] == 'a' || str[i] == 'e' || str[i] == 'i'|| str[i] == 'o' || str[i] == 'u'|| str[i] == 'A' || str[i] == 'E'|| str[i] == 'I' || str[i] == 'O'|| str[i] == 'U') { vowels++; } } cout << "Number of vowels in the string: " << vowels << endl; return 0; 
}

输出：

Number of vowels in the string: 9

10. 编写程序删除字符串中的元音

// C++ Program to remove the vowels from a string 
#include <cstring> 
#include <iostream> 
using namespace std; int main() 
{ int j = 0; string str = "GeeksforGeeks"; for (int i = 0; str[i] != '\0'; i++) { if (str[i] != 'a' && str[i] != 'e' && str[i] != 'i'&& str[i] != 'o' && str[i] != 'u'&& str[i] != 'A' && str[i] != 'E'&& str[i] != 'I' && str[i] != 'O'&& str[i] != 'U') { str[j++] = str[i]; } } while (j < str.size()) { str[j] = '\0'; j++; } cout << "String without vowels: " << str << endl; return 0; 
}

输出：

String without vowels: GksfrGks

11. 编写程序删除字符串中除字母以外的所有字符

// C++ Programto remove all characters from a string except 
// alphabets 
#include <cctype> 
#include <iostream> 
#include <string> using namespace std; string remove_non_alphabets(string str) 
{ string result = ""; for (char c : str) { if (isalpha(c)) { result += c; } } return result; 
} int main() 
{ string str = "Gee$ksfor$geeks"; cout << "Alphabets only: " << remove_non_alphabets(str) << endl; return 0; 
}

输出：

Alphabets only: Geeksforgeeks

12. 编写程序删除字符串中的空格

// C++ Program to remove spaces from a string 
#include <iostream> 
#include <string> using namespace std; string remove_spaces(string str) 
{ string result = ""; for (char c : str) { if (c != ' ') { result += c; } } return result; 
} int main() 
{ string str = "Gfg to the moon"; cout << "Without spaces: " << remove_spaces(str) << endl; return 0; 
}

输出：

Without spaces: Gfgtothemoon

13. 编写程序求前N个自然数的和

// C++ program to find 
// Sum of first 
// n natural numbers. 
#include <iostream> 
using namespace std; // Function to find sum 
int findSum(int n) 
{ int sum = 0; for (int i = 1; i <= n; i++) sum = sum + i; return sum; 
} int main() 
{ int n = 7; cout << findSum(n); return 0; 
}

输出：

28

14. 编写一个用循环求数的阶乘的程序

// C++ program to find factorial using loops 
#include <bits/stdc++.h> 
using namespace std; // function to find factorial 
int factorial(int n) 
{ int fact = 1; while (n > 1) { fact *= n; n--; } return fact; 
} // driver code 
int main() 
{ int num = 5; cout << factorial(num); return 0; 
}

输出：

120

15. 编写程序判断是否为闰年

// C++ program to check if a given 
// year is leap year or not 
#include <iostream> 
using namespace std; bool checkYear(int year) 
{ // leap year if (year % 400 == 0) return true; // Not leap year if (year % 100 == 0) return false; // leap year if (year % 4 == 0) return true; // Not leap year return false; 
} int main() 
{ int year = 2000; if (checkYear(year)) cout << "Leap Year"; elsecout << "Not a Leap Year"; return 0; 
}

输出：

Leap Year

16. 编写程序判断是否为素数

// C++ program to check if a 
// Number is prime 
#include <iostream> 
using namespace std; bool isPrime(int n) 
{ // base condition if (n <= 1) return false; // Check from 2 to n-1 for (int i = 2; i < n; i++) if (n % i == 0) return false; return true; 
} int main() 
{ isPrime(21) ? cout << " true\n" : cout << " false\n"; isPrime(17) ? cout << " true\n" : cout << " false\n"; return 0; 
}

输出：

false
true

17. 编写程序检查是否为回文

// C++ program to check if a 
// number is Palindrome or not 
#include <iostream> 
using namespace std; // Function to check Palindrome 
bool checkPalindrome(int n) 
{ int ans = 0; int temp = n; while (temp != 0) { ans = (ans * 10) + (temp % 10); temp = temp / 10; } return (ans == n); 
} int main() 
{ int n = 12321; if (checkPalindrome(n) == 1) { cout << "Yes\n"; } else { cout << "No\n"; } return 0; 
}

输出：

Yes

18. 编写程序检查一个数字是否为Armstrong数

// C++ Program to check 
// if number is Armstrong 
// or not 
#include <iostream> 
using namespace std; int main() 
{ int n = 153; int temp = n; int ans = 0; // function to calculate // the sum of individual digits while (n > 0) { int rem = n % 10; ans = (ans) + (rem * rem * rem); n = n / 10; } // condition to check if (temp == ans) { cout << ("Yes, it is Armstrong Number"); } else { cout << ("No, it is not an Armstrong Number"); } return 0; 
}

输出：

Yes, it is Armstrong Number

19. 编写程序计算斐波那契数列的第N项

// C++ Program to Find the 
// Nth Term of the Fibonacci Series 
#include <iostream> 
using namespace std; int fib(int n) 
{ int first = 0, second = 1, ans; if (n == 0) return first; for (int i = 2; i <= n; i++) { ans = first + second; first = second; second = ans; } return ans; 
} int main() 
{ int n = 13; cout << fib(n); return 0; 
}

输出：

233

20. 编写程序计算两个数的最大公约数

// C++ program to find 
// GCD of two numbers 
#include <iostream> using namespace std; // Function to return gcd of a and b 
int gcd(int a, int b) 
{ int result = min(a, b); while (result > 0) { if (a % result == 0 && b % result == 0) { break; } result--; } return result; 
} int main() 
{ int a = 54, b = 33; cout << "GCD: " << gcd(a, b); return 0; 
}

输出：

GCD: 3

21. 编写程序计算两个数字的最小公倍数（LCM）

// C++ program to 
// Find LCM of two numbers 
#include <iostream> 
using namespace std; long long gcd(long long int a, long long int b) 
{ if (b == 0) return a; return gcd(b, a % b); 
} // Function to return LCM of two numbers 
long long lcm(int a, int b) 
{ long long result = (a / gcd(a, b)) * b; return result; 
} int main() 
{ int a = 24, b = 13; cout << "LCM : " << lcm(a, b); return 0; 
}

输出：

LCM : 312

22. 编写程序求二次方程的根

// C++ program to find 
// Roots of a quadratic equation 
#include <iostream> 
#include <math.h> 
using namespace std; // Prints roots of quadratic equation ax*2 + bx + c 
void findRoots(int a, int b, int c) 
{ // If a is 0, then equation is not quadratic if (a == 0) { cout << "Invalid"; return; } // Formulae to calculate D int d = b * b - 4 * a * c; // Formulae to calculate // square root of D double sqrt_val = sqrt(abs(d)); // Conditons for checking root if (d > 0) { cout << "Roots are real and different \n"; cout << (double)(-b + sqrt_val) / (2 * a) << "\n"<< (double)(-b - sqrt_val) / (2 * a); } else if (d == 0) { cout << "Roots are real and same \n"; cout << -(double)b / (2 * a); } else { cout << "Roots are complex \n"; cout << -(double)b / (2 * a) << " + i"<< sqrt_val / (2 * a) << "\n"<< -(double)b / (2 * a) << " - i"<< sqrt_val / (2 * a); } 
} int main() 
{ int a = 1, b = 4, c = 4; findRoots(a, b, c); return 0; 
}

输出：

Roots are real and same 
-2

23. 编写程序查找数组中的最小和最大的元素

// C++ code to for 
// Finding the minimum 
// And maximum of the array 
#include <iostream> 
using namespace std; // Function to find the minimum 
// and maximum of the array 
void findMinMax(int arr[], int n) 
{ int mini = arr[0]; int maxi = arr[0]; for (int i = 0; i < n; i++) { if (arr[i] < mini) { mini = arr[i]; } else if (arr[i] > maxi) { maxi = arr[i]; } } cout << "Min: " << mini << endl; cout << "Max: " << maxi << endl; 
} int main() 
{ int arr[] = { 1, 2, 3, 4, 5 }; int N = sizeof(arr) / sizeof(arr[0]); findMinMax(arr, N); return 0; 
}

输出：

Min: 1
Max: 5

24. 编写程序查找数组中第二小的元素

// C++ program to find 
// Second smallest elements 
#include <climits> 
#include <iostream> 
using namespace std; void print2Smallest(int arr[], int n) 
{ int first, second; if (n < 2) { cout << " Invalid Input "; return; } first = second = INT_MAX; for (int i = 0; i < n; i++) { // If current element is smaller than first // Then update both first and second if (arr[i] < first) { second = first; first = arr[i]; } // If arr[i] is in between first and second // Then update second else if (arr[i] < second && arr[i] != first) second = arr[i]; } if (second == INT_MAX) cout << "There is no second smallest element\n"; elsecout << " Second smallest element is " << second << endl; 
} int main() 
{ int arr[] = { 21, 3, 15, 41, 34, 10 }; int n = sizeof(arr) / sizeof(arr[0]); print2Smallest(arr, n); return 0; 
}

输出：

Second smallest element is 10

25. 编写程序计算数组所有元素的和

// C++ Program to calculate 
// sum of elements in an array 
#include <iostream> 
using namespace std; int sum(int arr[], int n) 
{ int sum = 0; for (int i = 0; i < n; i++) sum += arr[i]; return sum; 
} int main() 
{ int arr[] = { 1, 23, 54, 12, 9 }; int n = sizeof(arr) / sizeof(arr[0]); cout << "Sum: " << sum(arr, n); return 0; 
}

输出：

Sum: 99

26. 编写程序检查给定字符串是否为回文

// C++ program for checking 
// if it is Palindrome or not 
#include <iostream> 
using namespace std; string isPalindrome(string S) 
{ for (int i = 0; i < S.length() / 2; i++) { if (S[i] != S[S.length() - i - 1]) { return "No"; } } return "Yes"; 
} int main() 
{ string S = "GeekeeG"; cout << isPalindrome(S); return 0; 
}

输出：

Yes

27. 编写程序检查两个字符串是否互为异位字符串

// C++ program to check if two strings 
// Are anagrams of each other 
#include <iostream> 
using namespace std; #define NO_OF_CHARS 256 bool areAnagram(char* str1, char* str2) 
{ // Create 2 count arrays and initialize all values as 0 int count1[NO_OF_CHARS] = { 0 }; int count2[NO_OF_CHARS] = { 0 }; int i; // For each character in input strings, increment count // in the corresponding count array for (i = 0; str1[i] && str2[i]; i++) { count1[str1[i]]++; count2[str2[i]]++; } if (str1[i] || str2[i]) return false; // Compare count arrays for (i = 0; i < NO_OF_CHARS; i++) if (count1[i] != count2[i]) return false; return true; 
} int main() 
{ char str1[] = "Geek"; char str2[] = "for"; if (areAnagram(str1, str2)) cout << "The two strings are anagram of each other"; elsecout << "The two strings are not anagram of each ""other"; return 0; 
}

输出：

The two strings are not anagram of each other

28. 编写程序打印以下的钻石图案

             *************************

// C++ program to print 
// Diamond shape 
#include <iostream> 
using namespace std; void printDiamond(int n) 
{ int space = n - 1; for (int i = 0; i < n; i++) { for (int j = 0; j < space; j++) cout << " "; // Print i+1 stars for (int j = 0; j <= i; j++) cout << "* "; cout << endl; space--; } space = 0; // run loop (parent loop) for (int i = n; i > 0; i--) { for (int j = 0; j < space; j++) cout << " "; // Print i stars for (int j = 0; j < i; j++) cout << "* "; cout << endl; space++; } 
} int main() 
{ printDiamond(5); return 0; 
}

输出：

    * * * * * * * * * * 
* * * * * 
* * * * * * * * * * * * * * * 

29. 编写打印金字塔图案的程序

              ****************

// C++ Program to 
// Print Pyramid pattern 
#include <iostream> 
using namespace std; void pattern(int n) 
{ int k = 2 * n - 2; for (int i = 0; i < n; i++) { for (int j = 0; j < k; j++) cout << " "; k = k - 1; for (int j = 0; j <= i; j++) { // Printing stars cout << "* "; } cout << endl; } 
} int main() 
{ int n = 5; pattern(n); return 0; 
}

输出：

        * * * * * * * * * * * * * * * 

30. 编写程序打印沙漏图案

* * * * * * * * ** * * * * * ** * * * ** * *** * *    * * * * ** * * * * * *    
* * * * * * * * *

// C Program to print hourglass pattern 
#include <iostream> 
using namespace std; // function to print hourglass pattern 
void hourglass(int rows) 
{ // first outer loop to iterate each row for (int i = 0; i < 2 * rows - 1; i++) { // assigning comparator int comp; if (i < rows) { comp = 2 * i + 1; } else { comp = 2 * (2 * rows - i) - 3; } // first inner loop to print leading spaces for (int j = 0; j < comp; j++) { cout << ' '; } // second inner loop to print star * for (int k = 0; k < 2 * rows - comp; k++) { cout << "* "; } cout << '\n'; } 
} int main() 
{ hourglass(5); return 0; 
}

输出：

 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 

31. 编写程序打印旋转沙漏图案

*                         * 
* *                     * * 
* * *                 * * * 
* * * *             * * * * 
* * * * *         * * * * * 
* * * * * *     * * * * * * 
* * * * * * * * * * * * * * 
* * * * * *     * * * * * * 
* * * * *         * * * * * 
* * * *             * * * * 
* * *                 * * * 
* *                     * * 
*                         * 

// C++ Program to print 
// star pattern given 
#include <iostream> 
using namespace std; void pattern(int n) 
{ for (int i = 0; i <= n; i++) { for (int j = 0; j <= i; j++) { cout << "* "; } int spaces = 2 * (n - i); for (int j = 0; j < spaces; j++) { cout << " "; } for (int j = 0; j <= i; j++) { cout << "* "; } cout << endl; } // Printing bottom part. for (int i = n - 1; i >= 0; i--) { for (int j = 0; j <= i; j++) { cout << "* "; } int spaces = 2 * (n - i); for (int j = 0; j < spaces; j++) { cout << " "; } for (int j = 0; j <= i; j++) { cout << "* "; } cout << endl; } 
} int main() 
{ int n = 5; pattern(n); return 0; 
}

输出：

*                     * 
* *                 * * 
* * *             * * * 
* * * *         * * * * 
* * * * *     * * * * * 
* * * * * * * * * * * * 
* * * * *     * * * * * 
* * * *         * * * * 
* * *             * * * 
* *                 * * 
*                     * 

32. 编写打印简单金字塔图案的程序

// C++ Program to print a simple pyramid 
#include <iostream> 
using namespace std; int main() 
{ int rows = 5; for (int i = 1; i <= rows; i++) { for (int j = rows; j >= i; j--) { cout << " "; } for (int k = 1; k <= (2 * i - 1); k++) { cout << "*"; } cout << endl; } return 0; 
}

输出：

     *************************

33. 编写程序打印倒金字塔

// C++ Program to print inverted pyramid 
#include <iostream> 
using namespace std; int main() 
{ int rows = 5; for (int i = rows; i >= 1; i--) { for (int j = rows; j > i; j--) { cout << " "; } for (int k = 1; k <= (2 * i - 1); k++) { cout << "*"; } cout << endl; } return 0; 
}

输出：

*************************

34. 编写程序打印三角形星形图案

// C++ Program to print a triangle star patter 
#include <iostream> 
using namespace std; int main() 
{ int rows; rows = 5; for (int i = 1; i <= rows; i++) { for (int j = 1; j <= i; j++) { cout << "*"; } cout << endl; } return 0; 
}

输出：

*
**
***
****
*****

35. 编写程序打印Floyd三角形

// C Program to print the Floyd's Triangle 
#include <stdio.h> int main() 
{ int rows = 4; int n = 1; // outer loop to print all rows for (int i = 0; i < rows; i++) { // innter loop to print abphabet in each row for (int j = 0; j <= i; j++) { printf("%d ", n++); } printf("\n"); } return 0; 
}

输出：

1 
2 3 
4 5 6 
7 8 9 10 

36. 编写程序打印Pascal三角形

            1   1   1   1   2   1   1   3   3   1   1   4   6   4   1   1   5   10   10   5   1 

// C++ program to print 
// Pascal’s Triangle 
#include <iostream> 
using namespace std; void printPascal(int n) 
{ int arr[n][n]; for (int line = 0; line < n; line++) { // Every line has number of integers // equal to line number for (int i = 0; i <= line; i++) { // First and last values in every row are 1 if (line == i || i == 0) arr[line][i] = 1; elsearr[line][i] = arr[line - 1][i - 1] + arr[line - 1][i]; cout << arr[line][i] << " "; } cout << "\n"; } 
} int main() 
{ int n = 6; printPascal(n); return 0; 
}

输出：

1 
1 1 
1 2 1 
1 3 3 1 
1 4 6 4 1 
1 5 10 10 5 1 

37. 编写程序逆序打印给定字符串

// C++ Program to reversea string 
#include <cstring> 
#include <iostream> 
using namespace std; int main() 
{ int len; string str = "GeeksforGeeks"; len = str.size(); cout << "Reverse of the string: "; for (int i = len - 1; i >= 0; i--) { cout << str[i]; } cout << endl; return 0; 
}

输出：

Reverse of the string: skeeGrofskeeG

38. 编写C++程序，使用递归逆序打印给定字符串

// C++ Program to 
// Reverse string using 
// recursion 
#include <iostream> 
using namespace std; void reverse_str(string& s, int n, int i) 
{ if (n <= i) { return; } swap(s[i], s[n]); reverse_str(s, n - 1, i + 1); 
} int main() 
{ string str = "GeeksforGeeks"; reverse_str(str, str.length() - 1, 0); cout << str << endl; 
}

输出：

skeeGrofskeeG

39. 编写程序，使用递归判断给定的字符串是否为回文

// C++ program to check 
// Whether a given number 
// Is palindrome or not 
#include <bits/stdc++.h> 
using namespace std; bool isPalRec(char str[], int s, int n) 
{ // If there is only one character if (s == n) return true; // If first and last // characters do not match if (str[s] != str[n]) return false; if (s < n + 1) return isPalRec(str, s + 1, n - 1); return true; 
} bool isPalindrome(char str[]) 
{ int n = strlen(str); if (n == 0) return true; return isPalRec(str, 0, n - 1); 
} int main() 
{ char str[] = "GeeKeeG"; if (isPalindrome(str)) cout << "Yes"; elsecout << "No"; return 0; 
}

输出：

Yes

40. 使用递归计算字符串长度

// C++ Program for calculating 
// the length of string 
#include <iostream> 
using namespace std; int cal(char* str) 
{ // base condition if (*str == '\0') return 0; elsereturn 1 + cal(str + 1); 
} int main() 
{ char str[] = "GeeksforGeeks"; cout << cal(str); return 0; 
}

输出：

13

41. 使用递归计算一个数的阶乘

// C++ program to calculate 
// Factorial of given number 
#include <iostream> 
using namespace std; unsigned long long factorial(unsigned long long n) 
{ if (n == 0 || n == 1) return 1; return n * factorial(n - 1); 
} int main() 
{ unsigned long long num = 15; cout << "Factorial of " << num << " is "<< factorial(num) << endl; return 0; 
}

输出：

Factorial of 15 is 1307674368000

42. 编写程序计算字符串中数字的总和

// C++ Program to count the sume of numbers in a string 
#include <iostream> 
#include <sstream> 
#include <string> using namespace std; int sum_of_numbers(string str) 
{ int sum = 0; for (char ch : str) { if (isdigit(ch)) { sum += ch - '0'; } } return sum; 
} int main() 
{ string str; str = "1234"; cout << "Sum of numbers: " << sum_of_numbers(str) << endl; return 0; 
}

输出：

Sum of numbers: 10

43. 编写一个程序，在不使用分号的情况下打印N以内的所有自然数

// C++ program to print all natural numbers upto 
// N without using semi-colon 
#include <iostream> using namespace std; 
#define N 10 int main() 
{ static int x = 1; if (cout << x << " " && x++ < N && main()) { } return 0; 
}

输出：

1 2 3 4 5 6 7 8 9 10 

44. 编写一个程序，在不使用任何额外变量的情况下交换两个变量的值

// C++ program to check 
// If two numbers are equal 
#include <iostream> 
using namespace std; int main() 
{ int x = 3; int y = 4; cout << "X : " << x << endl; cout << "Y : " << y << endl; x = x + y; y = x - y; x = x - y; cout << endl; cout << "After:" << endl; cout << "X : " << x << endl; cout << "Y : " << y << endl; return 0; 
}

输出：

X : 3
Y : 4After:
X : 4
Y : 3

45. 编写程序，使用补码(~)运算符打印无符号整数类型的最大值

// C++ program to print maximum value of 
// unsigned int. 
#include <iostream> using namespace std; int main() 
{ unsigned int max; max = 0; max = ~max; cout << "Max value possible : " << max; return 0; 
}

输出：

Max value possible : 4294967295

46. 不使用算术或比较运算符，检查两个数字的相等性

// C++ Program to equality of 
// Two numbers without using 
// Arithmetic or comparison operator 
#include <iostream> 
using namespace std; int main() 
{ int a = 10, b = 10; if (a ^ b) cout << "Not-Equal"; elsecout << "Equal"; return 0; 
}

输出

Equal

47. 编写一个程序，在不使用比较运算符的情况下求两个数的最大值和最小值

// C++ program to find 
// maximum and minimum of 
// Two numbers without using 
// loop and conditions 
#include <iostream> using namespace std; int main() 
{ int a = 5, b = 10; cout << "max :" << (((a + b) + abs(a - b)) / 2) << endl; cout << "min :" << (((a + b) - abs(a - b)) / 2) << endl; return 0; 
}

输出：

max :10
min :5

48. 编写八进制到十进制转换程序

// C++ Program to convert ocatal to decimal 
#include <cmath> 
#include <iostream> using namespace std; int main() 
{ int oct, dec = 0, place = 0; // 67 is an octal number with binary equivalent 110000 oct = 67; int temp = oct; while (temp) { int lastDigit = temp % 10; temp /= 10; dec += lastDigit * pow(8, place); ++place; } cout << "Decimal equivalent is: " << dec << endl; return 0; 
}

输出：

Decimal equivalent is: 55

49. 编写十六进制到十进制转换的程序

// C++ Program to convert hexadecimal to decimal conversion 
#include <cmath> 
#include <iostream> using namespace std; int hexToDecimal(char hexDigit) 
{ if (hexDigit >= '0' && hexDigit <= '9') { return int(hexDigit - '0'); } else if (hexDigit >= 'A' && hexDigit <= 'F') { return int(hexDigit - 'A' + 10); } else if (hexDigit >= 'a' && hexDigit <= 'f') { return int(hexDigit - 'a' + 10); } return -1; 
} int main() 
{ string hex; int decimal = 0, place = 0; hex = "67"; int n = hex.length(); for (int i = n - 1; i >= 0; i--) { int digit = hexToDecimal(hex[i]); decimal += digit * pow(16, place); place++; } cout << "Decimal equivalent " << decimal << endl; return 0; 
}

输出：

Decimal equivalent 103

50. 编写一个十进制到二进制转换的程序

// c++ program to convert decimal to binary 
#include <bitset> 
#include <iostream> using namespace std; int main() 
{ int decimal = 7; // simplest method to convert decimal to binary bitset<32> binary(decimal); cout << "Binary equivalent: " << binary << endl; return 0; 
}

输出：

Binary equivalent: 00000000000000000000000000000111

51. 编写一个程序进行十进制八进制转换

// C++ Program to convert decimal to octal equivalent 
#include <cmath> 
#include <iostream> using namespace std; int main() 
{ int decimal, octal = 0, place = 1; decimal = 55; int temp = decimal; while (temp) { int lastDigit = temp % 8; temp /= 8; octal += lastDigit * place; place *= 10; } cout << "Octal equivalent " << octal << endl; return 0; 
}

输出

Octal equivalent 67

52. 编写十进制到十六进制转换程序

// C++ program to convert decimal to hexadecimal 
#include <cmath> 
#include <iostream> 
#include <string> using namespace std; string decimalToHexa(int decimal) 
{ string hexadecimal = ""; char hexaDecimals[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; while (decimal > 0) { int remainder = decimal % 16; hexadecimal = hexaDecimals[remainder] + hexadecimal; decimal /= 16; } return hexadecimal; 
} int main() 
{ int decimal = 103; cout << "Hexadecimal equivalent: "<< decimalToHexa(decimal) << endl; return 0; 
}

输出：

Hexadecimal equivalent: 67

53. 编写二进制到八进制转换程序

// C++ implementation to convert a binary number 
// to octal number 
#include <bits/stdc++.h> 
using namespace std; // function to create map between binary 
// number and its equivalent octal 
void createMap(unordered_map<string, char>* um) 
{ (*um)["000"] = '0'; (*um)["001"] = '1'; (*um)["010"] = '2'; (*um)["011"] = '3'; (*um)["100"] = '4'; (*um)["101"] = '5'; (*um)["110"] = '6'; (*um)["111"] = '7'; 
} // Function to find octal equivalent of binary 
string convertBinToOct(string bin) 
{ int l = bin.size(); int t = bin.find_first_of('.'); // length of string before '.' int len_left = t != -1 ? t : l; // add min 0's in the beginning to make // left substring length divisible by 3 for (int i = 1; i <= (3 - len_left % 3) % 3; i++) bin = '0' + bin; // if decimal point exists if (t != -1) { // length of string after '.' int len_right = l - len_left - 1; // add min 0's in the end to make right // substring length divisible by 3 for (int i = 1; i <= (3 - len_right % 3) % 3; i++) bin = bin + '0'; } // create map between binary and its // equivalent octal code unordered_map<string, char> bin_oct_map; createMap(&bin_oct_map); int i = 0; string octal = ""; while (1) { // one by one extract from left, substring // of size 3 and add its octal code octal += bin_oct_map[bin.substr(i, 3)]; i += 3; if (i == bin.size()) break; // if '.' is encountered add it to result if (bin.at(i) == '.') { octal += '.'; i++; } } // required octal number return octal; 
} // Driver program to test above 
int main() 
{ string bin = "1111001010010100001.010110110011011"; cout << "Octal number = " << convertBinToOct(bin); return 0; 
}

输出：

Octal number = 1712241.26633

54. 编写八进制到二进制转换的程序

// C++ program to convert 
// Octal number to Binary #include <iostream> 
using namespace std; // Function to convert an 
// Octal to Binary Number 
string OctToBin(string octnum) 
{ long int i = 0; string binary = ""; while (octnum[i]) { switch (octnum[i]) { case '0': binary += "000"; break; case '1': binary += "001"; break; case '2': binary += "010"; break; case '3': binary += "011"; break; case '4': binary += "100"; break; case '5': binary += "101"; break; case '6': binary += "110"; break; case '7': binary += "111"; break; default: cout << "\nInvalid Octal Digit " << octnum[i]; break; } i++; } return binary; 
} // Driver code 
int main() 
{ // Get the Hexadecimal number string octnum = "345"; // Convert Octal to Binary cout << "Equivalent Binary Value = "<< OctToBin(octnum); return 0; 
}

输出：

Equivalent Binary Value = 011100101

55. 编写一个程序来实现封装的使用

// C++ Program to implement 
// The concept of Encapsulation 
#include <iostream> 
using namespace std; class Encapsulation { 
private: // data hidden from outer functions int x; public: // function to set value of // variable x void setter(int a) { x = a; } // function to return value of // variable x int getter() { return x; } 
}; int main() 
{ Encapsulation obj; obj.setter(13); cout << obj.getter(); return 0; 
}

输出：

13

56. 编写一个实现抽象概念的程序

// C++ Program to implement 
// Working of Abstraction 
#include <iostream> 
using namespace std; class implementAbstraction { 
private: int p, q; public: // method to set values of // private members void setter(int x, int y) { p = x; q = y; } void display() { cout << "p = " << p << endl; cout << "q = " << q << endl; } 
}; int main() 
{ implementAbstraction obj; obj.setter(1, 2); obj.display(); return 0; 
}

输出：

p = 1
q = 2

57. 编写程序实现编译时多态性或函数重载的概念

// C++ program to demonstrate 
// Function overloading or 
// Compile-time Polymorphism 
#include <iostream> using namespace std; class Geeks { 
public: // Function same name different // Parameters void func(int x) { cout << "value of x is " << x << endl; } void func(double x) { cout << "value of x is " << x << endl; } void func(int x, int y) { cout << "value of x and y is " << x << ", " << y << endl; } 
}; int main() 
{ Geeks obj1; // Function being called depends // on the parameters passed // func() is called with int value obj1.func(10); // func() is called with double value obj1.func(5.321); // func() is called with 2 int values obj1.func(94, 32); return 0; 
}

输出

value of x is 10
value of x is 5.321
value of x and y is 94, 32

58. 编写一个实现运算符重载概念的程序

// C++ program to demonstrate 
// Operator Overloading 
#include <iostream> 
using namespace std; class Complex { 
private: int real, imag; public: Complex(int r = 0, int i = 0) { real = r; imag = i; } // This is automatically called // when '+' is used Complex operator+(Complex const& obj) { Complex res; res.real = real + obj.real; res.imag = imag + obj.imag; return res; } void print() { cout << real << " + " << imag << "i\n"; } 
}; int main() 
{ Complex c1(15, 5), c2(3, 5); Complex c3 = c1 + c2; c3.print(); 
}

输出：

18 + 10i

59. 编写一个程序来实现函数重写或运行时多态性的概念

// C++ program for implementation 
// of Function Overloading or 
// Compile time Polymorphism 
#include <iostream> 
using namespace std; class base { 
public: virtual void print() { cout << "print base class" << endl; } void show() { cout << "show base class" << endl; } 
}; class derived : public base { 
public: void print() { cout << "print derived class" << endl; } void show() { cout << "show derived class" << endl; } 
}; int main() 
{ base* bptr; derived d; bptr = &d; bptr->print(); // Non-virtual function, binded // at compile time bptr->show(); return 0; 
}

输出：

print derived class
show base class

60. 编写实现单继承的程序

// C++ Program to implement 
// Single level inheritance 
#include <iostream> 
#include <string.h> using namespace std; class Person { int id; char name[100]; public: void set_p(int id, char* name) { strcpy(this->name, name); this->id = id; } void display_p() { cout << endl << id << "\t" << name << "\t"; } 
}; class Student : private Person { char course[50]; int fee; public: void set_s(int id, char* name, char* course, int fee) { set_p(id, name); strcpy(this->course, course); this->fee = fee; } void display_s() { display_p(); cout << course << "\t" << fee << endl; } 
}; main() 
{ Student s; char name[] = "XYZ"; char course[] = "ABC"; s.set_s(132451, name, course, 100000); s.display_s(); return 0; 
}

输出

132451    XYZ    ABC    100000

61. 编写程序创建一个复数类

// C++ Program to create a class of complex numbers 
#include <bits/stdc++.h> 
using namespace std; // complex number datatype 
struct c { double real; double img; 
}; // complex clss 
class Complex { 
private: struct c num; public: // constructors Complex() {} Complex(double real, double img) { num.img = img; num.real = real; } Complex(Complex& var) { num.img = var.num.img; num.real = var.num.real; } // utility functions void print() { cout << num.real << " + i" << num.img << endl; } double imag() { return num.img; } double real() { return num.real; } // overloaded operators Complex operator+(Complex& obj1) { Complex var; var.num.real = num.real + obj1.num.real; var.num.img = num.img + obj1.num.img; return var; } Complex operator-(Complex& obj1) { Complex var; var.num.real = num.real - obj1.num.real; var.num.img = num.img - obj1.num.img; return var; } Complex operator*(Complex& obj1) { Complex var; var.num.real = num.real * obj1.num.real - num.img * obj1.num.img; var.num.img = num.real * obj1.num.img + num.img * obj1.num.real; return var; } 
}; // driver code 
int main() 
{ Complex a(11, 12), b(5, 8); Complex c; c = a + b; a.print(); b.print(); c.print(); return 0; 
}

输出

11 + i12
5 + i8
16 + i20

62. 编写一个程序来实现英寸-英尺系统

// C++ Program to create a class of inchFeet length system 
#include <bits/stdc++.h> 
using namespace std; // inch-feet length system datatype 
struct c { double feet; double inch; 
}; // inchFeet class 
class inchFeet { 
private: struct c length; public: // constructors inchFeet() {} inchFeet(double feet, double inch) { length.inch = inch; length.feet = feet; } inchFeet(inchFeet& var) { length.inch = var.length.inch; length.feet = var.length.feet; } // utility functions void print() { cout << length.feet << " feet and " << length.inch << " inches" << endl; } double inches() { return length.inch; } double feet() { return length.feet; } // overloaded operators inchFeet operator+(inchFeet& obj1) { inchFeet var; var.length.feet = length.feet + obj1.length.feet; var.length.inch = length.inch + obj1.length.inch; if (var.length.inch >= 12.0) { var.length.feet++; var.length.inch - 12.0; } return var; } inchFeet operator-(inchFeet& obj1) { inchFeet var; struct c temp = length; if (temp.feet > obj1.length.feet) { if (temp.inch < obj1.length.inch) { temp.feet--; temp.inch += 12; } var.length.feet = temp.feet - obj1.length.feet; var.length.inch = temp.inch - obj1.length.inch; } else { cout << "Negative Length is not Possible\n"; } return var; } 
}; // driver code 
int main() 
{ inchFeet a(11, 4), b(5, 8); inchFeet c; c = a - b; a.print(); b.print(); c.print(); return 0; 
}

输出

11 feet and 4 inches
5 feet and 8 inches
5 feet and 8 inches

63. 编写程序实现冒泡排序

// C++ program to implement 
// of Bubble sort 
#include <iostream> 
using namespace std; // Function to sort 
void bubbleSort(int arr[], int n) 
{ int i, j; for (i = 0; i < n - 1; i++) // Last i elements are already in place for (j = 0; j < n - i - 1; j++) if (arr[j] > arr[j + 1]) swap(arr[j], arr[j + 1]); 
} // Function to print an array 
void printArray(int arr[], int size) 
{ int i; for (i = 0; i < size; i++) cout << arr[i] << " "; cout << endl; 
} int main() 
{ int arr[] = { 3, 1, 4, 2, 5 }; int N = sizeof(arr) / sizeof(arr[0]); bubbleSort(arr, N); cout << "Sorted array: "; printArray(arr, N); return 0; 
}

输出

Sorted array: 1 2 3 4 5 

64. 编写程序实现插入排序

// C++ program to implement 
// Insertion sort 
#include <bits/stdc++.h> 
using namespace std; // Function to sort using 
// Insertion 
void insertion_sort(int arr[], int n) 
{ int i, key, j; for (i = 1; i < n; i++) { key = arr[i]; j = i - 1; while (j >= 0 && arr[j] > key) { arr[j + 1] = arr[j]; j = j - 1; } arr[j + 1] = key; } 
} // Print array 
void print_array(int arr[], int n) 
{ cout << " Sorted array:"; for (int i = 0; i < n; i++) cout << arr[i] << " "; cout << endl; 
} int main() 
{ int arr[] = { 1, 4, 3, 2, 5 }; int N = sizeof(arr) / sizeof(arr[0]); insertion_sort(arr, N); print_array(arr, N); return 0; 
}

输出

Sorted array:1 2 3 4 5 

65. 编写程序以实现选择排序

// C++ program to implement 
// Selection sort 
#include <iostream> 
using namespace std; // Swap function 
void swap(int* p, int* q) 
{ int temp = *p; *p = *q; *q = temp; 
} void selectionSort(int arr[], int n) 
{ int min_index; for (int i = 0; i < n - 1; i++) { min_index = i; for (int j = i + 1; j < n; j++) if (arr[j] < arr[min_index]) min_index = j; // Swap the found minimum element // with the first element if (min_index != i) swap(&arr[min_index], &arr[i]); } 
} // Print Array 
void printArray(int arr[], int size) 
{ int i; for (i = 0; i < size; i++) cout << arr[i] << " "; cout << endl; 
} int main() 
{ int arr[] = { 5, 4, 3, 2, 1 }; int n = sizeof(arr) / sizeof(arr[0]); selectionSort(arr, n); cout << "Sorted array: "; printArray(arr, n); return 0; 
}

输出

Sorted array: 1 2 3 4 5 

66. 编写程序实现归并排序

// C++ program to implement 
// Merge Sort 
#include <iostream> 
using namespace std; // Merge Sorted arrays 
void merge(int array[], int const left, int const mid, int const right) 
{ auto const subArrayOne = mid - left + 1; auto const subArrayTwo = right - mid; // Create temp arrays auto *leftArray = new int[subArrayOne], *rightArray = new int[subArrayTwo]; // Copy data to temp arrays leftArray[] and rightArray[] for (auto i = 0; i < subArrayOne; i++) leftArray[i] = array[left + i]; for (auto j = 0; j < subArrayTwo; j++) rightArray[j] = array[mid + 1 + j]; auto indexOfSubArrayOne = 0, indexOfSubArrayTwo = 0; int indexOfMergedArray = left; // Merge the temp arrays back into array[left..right] while (indexOfSubArrayOne < subArrayOne && indexOfSubArrayTwo < subArrayTwo) { if (leftArray[indexOfSubArrayOne] <= rightArray[indexOfSubArrayTwo]) { array[indexOfMergedArray] = leftArray[indexOfSubArrayOne]; indexOfSubArrayOne++; } else { array[indexOfMergedArray] = rightArray[indexOfSubArrayTwo]; indexOfSubArrayTwo++; } indexOfMergedArray++; } // Copying remaing elements while (indexOfSubArrayOne < subArrayOne) { array[indexOfMergedArray] = leftArray[indexOfSubArrayOne]; indexOfSubArrayOne++; indexOfMergedArray++; } while (indexOfSubArrayTwo < subArrayTwo) { array[indexOfMergedArray] = rightArray[indexOfSubArrayTwo]; indexOfSubArrayTwo++; indexOfMergedArray++; } delete[] leftArray; delete[] rightArray; 
} void mergeSort(int array[], int const begin, int const end) 
{ // base condition if (begin >= end) return; auto mid = begin + (end - begin) / 2; mergeSort(array, begin, mid); mergeSort(array, mid + 1, end); merge(array, begin, mid, end); 
} // Print Array 
void print_array(int A[], int size) 
{ for (auto i = 0; i < size; i++) cout << A[i] << " "; 
} int main() 
{ int arr[] = { 5, 6, 3, 10, 1, 4, 9 }; auto arr_size = sizeof(arr) / sizeof(arr[0]); cout << "Array: "; print_array(arr, arr_size); mergeSort(arr, 0, arr_size - 1); cout << "\nSorted array: "; print_array(arr, arr_size); return 0; 
}

输出：

Array: 5 6 3 10 1 4 9 
Sorted array: 1 3 4 5 6 9 10 

67. 编写程序实现快速排序

// C++ Program to implement 
// QuickSort 
#include <iostream> 
using namespace std; // Swap elements 
void swap(int* a, int* b) 
{ int t = *a; *a = *b; *b = t; 
} // Partition function to check pivot location 
int partition(int arr[], int low, int high) 
{ int pivot = arr[high]; // pivot int i = (low - 1); for (int j = low; j <= high - 1; j++) { // If current element is smaller than the pivot if (arr[j] < pivot) { i++; swap(&arr[i], &arr[j]); } } swap(&arr[i + 1], &arr[high]); return (i + 1); 
} // Quick Sort function 
void quickSort(int arr[], int low, int high) 
{ if (low < high) { // pi is partitioning index, arr[p] is now // at right place int pi = partition(arr, low, high); // Separately sort elements before // partition and after partition quickSort(arr, low, pi - 1); quickSort(arr, pi + 1, high); } 
} // Print Array 
void printArray(int arr[], int size) 
{ int i; for (i = 0; i < size; i++) cout << arr[i] << " "; cout << endl; 
} int main() 
{ int arr[] = { 2, 5, 6, 9, 1, 3, 4 }; int n = sizeof(arr) / sizeof(arr[0]); cout << "Array: "; printArray(arr, n); quickSort(arr, 0, n - 1); cout << "Sorted array: "; printArray(arr, n); return 0; 
}

输出

Array: 2 5 6 9 1 3 4 
Sorted array: 1 2 3 4 5 6 9 

68. 编写程序实现线性搜索

// C++ Program to implement 
// Linear Sort 
#include <iostream> 
using namespace std; int search(int arr[], int N, int x) 
{ int i; for (i = 0; i < N; i++) if (arr[i] == x) return i; return -1; 
} int main() 
{ int arr[] = { 5, 4, 1, 6, 10, 9, 23, 2 }; int x = 9; int N = sizeof(arr) / sizeof(arr[0]); int result = search(arr, N, x); if (result == -1) cout << "Element is not present in array"; elsecout << "Element is present at index " << result; return 0; 
}

输出：

Element is present at index 5

69. 编写一个程序实现二分查找

// C++ program to implement 
// Binary Search 
#include <iostream> 
using namespace std; // Binary Search Function 
int binarySearch(int arr[], int l, int r, int x) 
{ if (r >= l) { // Middle element int mid = l + (r - l) / 2; if (arr[mid] == x) return mid; if (arr[mid] > x) return binarySearch(arr, l, mid - 1, x); return binarySearch(arr, mid + 1, r, x); } // We reach here when element is not // present in array return -1; 
} int main(void) 
{ int arr[] = { 1, 2, 3, 4, 5, 6 }; int x = 5; int n = sizeof(arr) / sizeof(arr[0]); int result = binarySearch(arr, 0, n - 1, x); if (result == -1) cout << "Element is not present in array"; elsecout << "Element is present at index " << result; return 0; 
}

输出：

Element is present at index 4

70. 编写一个程序来查找vector中给定元素的下标

// C++ program to find the index 
// of an element in a vector 
#include <bits/stdc++.h> using namespace std; // print index of element 
void print_index(vector<int> v, int element) 
{ auto it = find(v.begin(), v.end(), element); // Condition if element found if (it != v.end()) { // Calculating the index // of element int index = it - v.begin(); cout << index << endl; } // No such element in vector else { cout << "-1" << endl; } 
} int main() 
{ vector<int> v = { 1, 2, 3, 4, 5, 6 }; int element = 5; print_index(v, element); return 0; 
}

输出

Output

71. 编写程序，使用STL删除数组中重复的元素

// C++ program to remove the 
// duplicate elements from the array 
// using STL in C++ 
#include <bits/stdc++.h> using namespace std; // Function to remove duplicate elements 
void removeDuplicates(int arr[], int n) 
{ int i; set<int> s; // Insert the array elements // into the set for (i = 0; i < n; i++) { s.insert(arr[i]); } set<int>::iterator it; // Print the array with duplicates removed cout << "\nAfter removing duplicates:\n"; for (it = s.begin(); it != s.end(); ++it) cout << *it << " "; cout << '\n'; 
} int main() 
{ int arr[] = { 1, 2, 2, 4, 3, 3, 2, 1 }; int n = sizeof(arr) / sizeof(arr[0]); // Print array cout << "\nBefore removing duplicates:\n"; for (int i = 0; i < n; i++) cout << arr[i] << " "; removeDuplicates(arr, n); return 0; 
}

输出

Before removing duplicates:
1 2 2 4 3 3 2 1 
After removing duplicates:
1 2 3 4 

72. 用STL编写数组降序排序程序

// C++ program to sort Array 
// in descending order 
#include <bits/stdc++.h> 
using namespace std; int main() 
{ // Get the array int arr[] = { 1, 2, 3, 4, 5, 6 }; // Compute the sizes int n = sizeof(arr) / sizeof(arr[0]); // Print the array cout << "Array: "; for (int i = 0; i < n; i++) cout << arr[i] << " "; // Sort the array in descending order sort(arr, arr + n, greater<int>()); // Print the array cout << "\nDescending Sorted Array:"; for (int i = 0; i < n; i++) cout << arr[i] << " "; return 0; 
}

输出

Array: 1 2 3 4 5 6 
Descending Sorted Array:6 5 4 3 2 1 

73. 编写程序计算给定字符串中每个单词的频率

// C++ program to calculate 
// frequency of each word 
// in given string 
#include <bits/stdc++.h> 
using namespace std; // Function to print frequency of each word 
void printFrequency(string str) 
{ map<string, int> M; string word = ""; for (int i = 0; i < str.size(); i++) { // if element is empty if (str[i] == ' ') { // If the current word // is not found then insert // current word with frequency 1 if (M.find(word) == M.end()) { M.insert(make_pair(word, 1)); word = ""; } else { M[word]++; word = ""; } } elseword += str[i]; } // Storing the last word of the string if (M.find(word) == M.end()) M.insert(make_pair(word, 1)); // Update the frequency elseM[word]++; // Traverse the map for (auto& it : M) { cout << it.first << " - " << it.second << endl; } 
} int main() 
{ string str = "Geeks For Geeks is for Geeks"; printFrequency(str); return 0; 
}

输出

For - 1
Geeks - 3
for - 1
is - 1

74. 编写一个程序，按原始顺序查找数组最大的 k 个元素

// C++ program to find k Maximum elements 
#include <bits/stdc++.h> 
using namespace std; // Function to print k Maximum elements 
void printMax(int arr[], int n, int k) 
{ int result[n], c[n]; // Coping the array a // into c and initialising for (int i = 0; i < n; i++) { c[i] = arr[i]; result[i] = 0; } for (int i = 0; i < k; i++) { int maxi = INT_MIN; int index; for (int j = 0; j < n; j++) { if (arr[j] > maxi) { maxi = arr[j]; index = j; } } // Assigning 1 in order // to mark the position // of all k maximum numbers result[index] = 1; arr[index] = INT_MIN; } // Printing elements for (int i = 0; i < n; i++) { if (result[i] == 1) cout << c[i] << " "; } 
} int main() 
{ int arr[] = { 50, 8, 45, 12, 25, 40, 84 }; int n = sizeof(arr) / sizeof(arr[0]); int k = 3; printMax(arr, n, k); return 0; 
}

输出

50 45 84 

75. 编写一个程序，使用STL找出给定集合的所有不同子集

// C++ code for the above approach: #include <bits/stdc++.h> 
using namespace std; void solve(vector<int>& arr, int n, set<vector<int> >& ans, vector<int> v, int i) 
{ // Base Condition if (i >= n) { ans.insert(v); return; } solve(arr, n, ans, v, i + 1); v.push_back(arr[i]); solve(arr, n, ans, v, i + 1); 
} vector<vector<int> > AllSubsets(vector<int> arr, int n) 
{ // Set of vectors to store // required unique subsets set<vector<int> > ans; sort(arr.begin(), arr.end()); vector<int> v; solve(arr, n, ans, v, 0); // Vector of vectors to store final result vector<vector<int> > res; while (!ans.empty()) { res.push_back(*ans.begin()); ans.erase(ans.begin()); } return res; 
} // Print Function 
void print(int N, vector<int>& A) 
{ vector<vector<int> > result = AllSubsets(A, N); // printing the output for (int i = 0; i < result.size(); i++) { cout << '('; for (int j = 0; j < result[i].size(); j++) { cout << result[i][j]; if (j < result[i].size() - 1) cout << " "; } cout << "), "; } cout << "\n"; 
} int main() 
{ int N = 3; vector<int> A = { 1, 2, 3 }; print(N, A); return 0; 
}

输出

(), (1), (1 2), (1 2 3), (1 3), (2), (2 3), (3), 

76. 编写一个程序遍历一个队列，但不删除其中的元素

// C++ program to iterate a 
// STL Queue by Creating 
// copy of given queue 
#include <iostream> 
#include <queue> 
using namespace std; 
int main() 
{ queue<int> q; // Inserting elements in queue q.push(1); q.push(2); q.push(3); q.push(4); q.push(5); // Copy queue queue<int> copy_queue = q; cout << "Queue elements :\n"; while (!copy_queue.empty()) { cout << copy_queue.front() << " "; copy_queue.pop(); } return 0; 
}

输出

Queue elements :
1 2 3 4 5 

77. 编写一个程序，使用数组实现栈

// C++ Program to implement stacks using array 
#include <iostream> 
using namespace std; // Maximum size of stack #define MAX 100 class Stack { 
private: int top; // Array to store stack elements int arr[MAX]; public: // Constructor to initialize top as -1 Stack() { top = -1; } // Function to push an element to the stack void push(int x) { if (top == MAX - 1) { cout << "Stack overflow" << endl; return; } arr[++top] = x; } // Function to pop an element from the stack int pop() { if (top == -1) { cout << "Stack underflow" << endl; return -1; } return arr[top--]; } // Function to check if stack is empty bool isEmpty() { return (top == -1); } // Function to return the top element of the stack int peek() { if (top == -1) { cout << "Stack is empty" << endl; return -1; } return arr[top]; } 
}; int main() 
{ Stack s; s.push(1); s.push(2); s.push(3); s.push(4); s.push(5); cout << "Popped element: " << s.pop() << endl; cout << "Top element: " << s.peek() << endl; return 0; 
}

输出

Popped element: 5
Top element: 4

78. 编写一个程序，使用数组实现队列

// C++ Program to implement queue using array 
#include <iostream> 
using namespace std; // Maximum size of the queue 
#define MAX 100 class Queue { 
private: int front, rear; // Array to store queue elements int arr[MAX]; public: // Constructor to initialize front and rear as -1 Queue() { front = rear = -1; } // Function to add an element to the queue void enqueue(int x) { if (rear == MAX - 1) { cout << "Error: Queue overflow" << endl; return; } arr[++rear] = x; if (front == -1) front = 0; } // Function to remove an element from the queue int dequeue() { if (front == -1) { cout << "Queue underflow" << endl; return -1; } int x = arr[front]; if (front == rear) front = rear = -1; elsefront++; return x; } // Function to check if queue is empty bool isEmpty() { return (front == -1); } // Function to return the front element of the queue int peek() { if (front == -1) { cout << "Queue is empty" << endl; return -1; } return arr[front]; } 
}; int main() 
{ Queue q; q.enqueue(1); q.enqueue(2); q.enqueue(3); q.enqueue(4); q.enqueue(5); cout << "Dequeued element: " << q.dequeue() << endl; cout << "Front element: " << q.peek() << endl; return 0; 
}

输出

Dequeued element: 1
Front element: 2

79. 编写程序使用队列实现栈

// C++ Program to implement 
// Stack using queue 
#include <bits/stdc++.h> using namespace std; class Stack { queue<int> q1, q2; public: void push(int x) { // Push x first in empty q2 q2.push(x); // Push all the remaining // elements in q1 to q2. while (!q1.empty()) { q2.push(q1.front()); q1.pop(); } // swap the names of two queues queue<int> q = q1; q1 = q2; q2 = q; } void pop() { // if no elements are there in q1 if (q1.empty()) return; q1.pop(); } int top() { if (q1.empty()) return -1; return q1.front(); } int size() { return q1.size(); } 
}; int main() 
{ Stack s; // Inserting elements in Stack s.push(1); s.push(2); s.push(3); s.push(4); cout << "Size: " << s.size() << endl; cout << s.top() << endl; s.pop(); cout << s.top() << endl; s.pop(); cout << s.top() << endl; cout << "Size: " << s.size() << endl; return 0; 
}

输出

Size: 4
4
3
2
Size: 2

80. 用STL中的链表写一个程序来实现栈

// C++ Program to implement 
// stack using list 
#include <bits/stdc++.h> using namespace std; // Template declared 
template <typename T> class Stack { 
public: list<T> l; int cs = 0; // current size of the stack // pushing an element into the stack void push(T d) { cs++; // increasing the current size of the stack l.push_front(d); } // popping an element from the stack void pop() { if (cs <= 0) { // cannot pop us stack does not contain an // elements cout << "Stack empty" << endl; } else { // decreasing the current size of the stack cs--; l.pop_front(); } } // if current size is 0 then stack is empty bool empty() { return cs == 0; } // getting the element present at the top of the stack T top() { return l.front(); } int size() { // getting the size of the stack return cs; } // printing the elements of the stack void print() { for (auto x : l) { cout << x << endl; } } 
}; 
int main() 
{ // Inserting elements in stack Stack<int> s; s.push(1); s.push(2); s.push(3); s.push(4); cout << "Size: " << s.size() << endl; cout << "Top element:" << s.top() << endl; s.pop(); cout << "Top element:" << s.top() << endl; s.pop(); cout << "Top element:" << s.top() << endl; cout << "Size:" << s.size() << endl; return 0; 
}

输出

Size: 4
Top element:4
Top element:3
Top element:2
Size:2

81. 编写一个程序，判断一个数组是否是另一个数组的子集

// C++ Program to check if 
// Array is a subset of another array or not #include <iostream> 
using namespace std; bool isSubset(int arr1[], int arr2[], int m, int n) 
{ int i = 0; int j = 0; for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { if (arr2[i] == arr1[j]) break; } if (j == m) return 0; } return 1; 
} int main() 
{ int arr1[] = { 1, 11, 31, 21, 30, 17 }; int arr2[] = { 11, 30, 17, 1 }; int m = sizeof(arr1) / sizeof(arr1[0]); int n = sizeof(arr2) / sizeof(arr2[0]); if (isSubset(arr1, arr2, m, n)) cout << "arr2 is subset of arr1 "; elsecout << "arr2 is not a subset of arr1"; return 0; 
}

输出

arr2 is subset of arr1 

82. Write a Program for Finding the Circular Rotation of an Array by K Positions

// C++ Program for Finding 
// Circular rotation of an array 
// by K positions 
#include <iostream> 
using namespace std; void Rotate(int arr[], int k, int n) 
{ // temp array int temp[n]; // Keepig track of the current index // of temp[] int t = 0; // Storing the n - d elements of // array arr[] to the front of temp[] for (int i = k; i < n; i++) { temp[t] = arr[i]; t++; } // Storing the first d elements of array arr[] // into temp for (int i = 0; i < k; i++) { temp[t] = arr[i]; t++; } // Copying the elements of temp[] in arr[] for (int i = 0; i < n; i++) { arr[i] = temp[i]; } 
} void print_array(int arr[], int n) 
{ for (int i = 0; i < n; i++) { cout << arr[i] << " "; } 
} int main() 
{ int arr[] = { 1, 2, 3, 4, 5 }; int N = sizeof(arr) / sizeof(arr[0]); int k = 2; // Function calling Rotate(arr, k, N); print_array(arr, N); return 0; 
}

输出

3 4 5 1 2 

83. 编写一个程序，按升序对前半部分进行排序，按降序对后半部分进行排序

// C++ Program to Sort first half 
// in ascending order and second half in descending 
#include <iostream> 
using namespace std; void ascDecFunc(int a[], int n) 
{ int temp; for (int i = 0; i < n - 1; i++) { for (int j = 0; j < n / 2; j++) { if (a[j] > a[j + 1]) { temp = a[j]; a[j] = a[j + 1]; a[j + 1] = temp; } } for (int j = n / 2; j < n - 1; j++) { if (a[j] < a[j + 1]) { temp = a[j]; a[j] = a[j + 1]; a[j + 1] = temp; } } } for (int i = 0; i < n; i++) cout << a[i] << " "; 
} int main() 
{ int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8 }; int len = sizeof(arr) / sizeof(arr[0]); ascDecFunc(arr, len); return 0; 
}

输出

1 2 3 4 8 7 6 5 

84.编写程序逆序打印给定字符串

// C++ program to demonstrate reverse 
// of a string using Last to First 
#include <iostream> 
using namespace std; void reverse(string str) 
{ for (int i = str.length() - 1; i >= 0; i--) cout << str[i]; 
} int main(void) 
{ string str = "GeeksforGeeks"; reverse(str); return (0); 
}

输出

skeeGrofskeeG

85. 编写一个程序，使用递归打印一个字符串的所有排列

// C++ Program to Print 
// Permutaions of string 
#include <iostream> 
#include <string> 
using namespace std; void permute(string s, string answer) 
{ if (s.length() == 0) { cout << answer << endl; return; } for (int i = 0; i < s.length(); i++) { char ch = s[i]; string left = s.substr(0, i); string right = s.substr(i + 1); string result = left + right; permute(result, answer + ch); } 
} int main() 
{ string s = "ABC"; string answer = ""; permute(s, answer); return 0; 
}

输出

ABC
ACB
BAC
BCA
CAB
CBA

86. 编写一个程序，按字典序打印给定字符串的所有排列

// C++ Program to Print all permutations 
// Of a given string in lexicographically sorted order 
#include <bits/stdc++.h> 
using namespace std; int compare(const void* a, const void* b) 
{ return (*(char*)a - *(char*)b); 
} void swap(char* a, char* b) 
{ char t = *a; *a = *b; *b = t; 
} int findCeil(char str[], char first, int l, int h) 
{ int ceilIndex = l; for (int i = l + 1; i <= h; i++) if (str[i] > first && str[i] < str[ceilIndex]) ceilIndex = i; return ceilIndex; 
} void Permutations(char str[]) 
{ int size = strlen(str); qsort(str, size, sizeof(str[0]), compare); bool isFinished = false; while (!isFinished) { cout << str << endl; int i; for (i = size - 2; i >= 0; --i) if (str[i] < str[i + 1]) break; if (i == -1) isFinished = true; else { int ceilIndex = findCeil(str, str[i], i + 1, size - 1); swap(&str[i], &str[ceilIndex]); qsort(str + i + 1, size - i - 1, sizeof(str[0]), compare); } } 
} int main() 
{ char str[] = "XYZ"; Permutations(str); return 0; 
}

输出

XYZ
XZY
YXZ
YZX
ZXY
ZYX

87. 编写一个程序，删除代数表达式中的括号

// C++ Program to remove brackets from an algebraic exp 
#include <iostream> 
#include <string> using namespace std; string remove_brackets(string str) 
{ string result = ""; for (char c : str) { if (c != '(' && c != ')') { result += c; } } return result; 
} int main() 
{ string str = "Geeks)(for)(geeks"; cout << "Without brackets: " << remove_brackets(str) << endl; return 0; 
}

88. 对单链表执行插入、删除和打印操作

// C++ Program to perform insertion, deletion, and print 
// operations in LL 
#include <iostream> using namespace std; struct Node { int data; Node* next; 
}; Node* head = nullptr; // Function to insert node in LL 
void insert(int data) 
{ Node* newNode = new Node(); newNode->data = data; newNode->next = head; head = newNode; 
} 
// function to delete node of LL 
void deleteNode(int data) 
{ Node *temp = head, *prev = nullptr; if (temp != nullptr && temp->data == data) { head = temp->next; delete temp; return; } while (temp != nullptr && temp->data != data) { prev = temp; temp = temp->next; } if (temp == nullptr) return; prev->next = temp->next; delete temp; 
} // function to print LL 
void printList() 
{ Node* temp = head; while (temp != nullptr) { cout << temp->data << " "; temp = temp->next; } cout << endl; 
} int main() 
{ insert(1); insert(2); insert(3); insert(4); insert(5); cout << "Linked List is \n"; printList(); deleteNode(3); cout << "Linked List after deletion of 3: "; printList(); return 0; 
}

输出

Linked List is 
5 4 3 2 1 
Linked List after deletion of 3: 5 4 2 1 

89. 对双链表执行插入、删除和打印操作

// C++ Program to implement insert, delete, and print 
// operation in doubly linked list 
#include <iostream> using namespace std; struct Node { int data; Node* next; Node* prev; 
}; class DoublyLinkedList { 
private: Node* head; public: DoublyLinkedList() : head(NULL) { } void insertAtStart(int data) { Node* newNode = new Node; newNode->data = data; newNode->next = head; newNode->prev = NULL; if (head != NULL) head->prev = newNode; head = newNode; } void deleteNode(int data) { Node* temp = head; while (temp != NULL && temp->data != data) temp = temp->next; if (temp == NULL) return; if (temp->prev != NULL) temp->prev->next = temp->next; elsehead = temp->next; if (temp->next != NULL) temp->next->prev = temp->prev; delete temp; } void printList() { Node* temp = head; while (temp != NULL) { std::cout << temp->data << " "; temp = temp->next; } std::cout << std::endl; } 
}; int main() 
{ DoublyLinkedList dll; dll.insertAtStart(1); dll.insertAtStart(2); dll.insertAtStart(3); dll.insertAtStart(4); dll.insertAtStart(5); std::cout << "Original Doubly Linked List: "; dll.printList(); dll.deleteNode(2); std::cout << "Doubly Linked List after deletion: "; dll.printList(); return 0; 
}

输出

Original Doubly Linked List: 5 4 3 2 1 
Doubly Linked List after deletion: 5 4 3 1 

90. 对循环链表执行插入、删除和打印操作

// C++ Program to implement insert, delete, and print in 
// circular linked list 
#include <iostream> struct Node { int data; Node* next; 
}; class CircularLinkedList { 
private: Node* head; public: CircularLinkedList() : head(NULL) { } void insertAtStart(int data) { Node* newNode = new Node; newNode->data = data; newNode->next = head; if (head == NULL) { head = newNode; newNode->next = head; } else { Node* temp = head; while (temp->next != head) temp = temp->next; temp->next = newNode; head = newNode; } } void deleteNode(int data) { Node* temp = head; if (temp == NULL) return; if (temp->next == head) { head = NULL; delete temp; return; } Node* prev = NULL; while (temp->next != head && temp->data != data) { prev = temp; temp = temp->next; } if (temp->data != data) return; prev->next = temp->next; if (temp == head) head = temp->next; delete temp; } void printList() { Node* temp = head; while (temp->next != head) { std::cout << temp->data << " "; temp = temp->next; } std::cout << temp->data << std::endl; } 
}; int main() 
{ CircularLinkedList cll; cll.insertAtStart(1); cll.insertAtStart(2); cll.insertAtStart(3); cll.insertAtStart(4); cll.insertAtStart(5); std::cout << "Original Circular Linked list "; cll.printList(); cll.deleteNode(2); std::cout << "Circular Linked List after deletion "; cll.printList(); return 0; 
}

输出

Original Circular Linked list 5 4 3 2 1
Circular Linked List after deletion 5 4 3 1

91. 二叉树的中序遍历

// C++ program Inorder Traversal 
#include <bits/stdc++.h> 
using namespace std; /* A binary tree node has data, pointer to left child 
and a pointer to right child */struct Node { int data; struct Node *left, *right; 
}; // Utility function to create a new tree node 
Node* newNode(int data) 
{ Node* temp = new Node; temp->data = data; temp->left = temp->right = NULL; return temp; 
} /* Given a binary tree, print its nodes in inorder*/
void printInorder(struct Node* node) 
{ if (node == NULL) return; /* first recur on left child */printInorder(node->left); /* then print the data of node */cout << node->data << " "; /* now recur on right child */printInorder(node->right); 
} int main() 
{ struct Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); // Function call cout << "Inorder traversal of binary tree is \n"; printInorder(root); return 0; 
}

输出

Inorder traversal of binary tree is 
4 2 5 1 3

92. 编写程序求一组正整数的所有子集

// C++ Program to find all subsets from the given set of 
// positive integers 
#include <bits/stdc++.h> using namespace std; void find_subset(vector<int>& A, vector<vector<int> >& ans, vector<int>& subset, int index) 
{ ans.push_back(subset); for (int i = index; i < A.size(); i++) { subset.push_back(A[i]); find_subset(A, ans, subset, i + 1); subset.pop_back(); } return; 
} vector<vector<int> > subsets(vector<int>& A) 
{ vector<int> subset; vector<vector<int> > ans; int index = 0; find_subset(A, ans, subset, index); return ans; 
} int main() 
{ vector<int> array = { 1, 2, 3, 4, 5 }; vector<vector<int> > ans = subsets(array); for (int i = 0; i < ans.size(); i++) { for (int j = 0; j < ans[i].size(); j++) cout << ans[i][j] << " "; cout << endl; } return 0; 
}

输出：

1 
1 2 
1 2 3 
1 2 3 4 
1 2 3 4 5 
1 2 3 5 
1 2 4 
1 2 4 5 
1 2 5 
1 3 
1 3 4 
1 3 4 5 
1 3 5 
1 4 
1 4 5 
1 5 
2 
2 3 
2 3 4 
2 3 4 5 
2 3 5 
2 4 
2 4 5 
2 5 
3 
3 4 
3 4 5 
3 5 
4 
4 5 
5 

93. 二叉树的先序遍历

// C++ program for preorder traversal 
#include <bits/stdc++.h> 
using namespace std; /* A binary tree node has data, pointer to left child 
and a pointer to right child */
struct Node { int data; struct Node *left, *right; 
}; // Utility function to create a new tree node 
Node* newNode(int data) 
{ Node* temp = new Node; temp->data = data; temp->left = temp->right = NULL; return temp; 
} /* Given a binary tree, print its nodes in preorder*/
void printPreorder(struct Node* node) 
{ if (node == NULL) return; /* first print data of node */cout << node->data << " "; /* then recur on left subtree */printPreorder(node->left); /* now recur on right subtree */printPreorder(node->right); 
} int main() 
{ struct Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); // Function call cout << "Preorder traversal of binary tree is \n"; printPreorder(root); return 0; 
}

输出

Preorder traversal of binary tree is 
1 2 4 5 3 

94. 二叉树的后序遍历

// C++ program for post order traversal 
#include <bits/stdc++.h> 
using namespace std; /* A binary tree node has data, pointer to left child 
and a pointer to right child */
struct Node { int data; struct Node *left, *right; 
}; // Utility function to create a new tree node 
Node* newNode(int data) 
{ Node* temp = new Node; temp->data = data; temp->left = temp->right = NULL; return temp; 
} /* Given a binary tree, print its nodes according to the 
"bottom-up" postorder traversal. */
void printPostorder(struct Node* node) 
{ if (node == NULL) return; // first recur on left subtree printPostorder(node->left); // then recur on right subtree printPostorder(node->right); // now deal with the node cout << node->data << " "; 
} int main() 
{ struct Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); // Function call cout << "Postorder traversal of binary tree is \n"; printPostorder(root); return 0; 
}

输出

Postorder traversal of binary tree is 
4 5 2 3 1 

95. 二叉树的层级遍历

// C++ program for post order traversal 
#include <bits/stdc++.h> 
using namespace std; /* A binary tree node has data, pointer to left child 
and a pointer to right child */
struct Node { int data; struct Node *left, *right; 
}; // Utility function to create a new tree node 
Node* newNode(int data) 
{ Node* temp = new Node; temp->data = data; temp->left = temp->right = NULL; return temp; 
} /* Given a binary tree, print its nodes according to the 
"bottom-up" postorder traversal. */
void printLevelOrder(struct Node* node) 
{ if (node == NULL) return; queue<struct Node*> q; while (node) { if (node->left) { q.push(node->left); } if (node->right) { q.push(node->right); } cout << node->data << " "; node = q.front(); q.pop(); } 
} int main() 
{ struct Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); // Function call cout << "Levelorder traversal of binary tree is \n"; printLevelOrder(root); return 0; 
}

输出

Levelorder traversal of binary tree is 
1 2 3 4 5 

96. 编写程序打印二叉树的俯视图

// C++ program for top view of a binary tree 
#include <bits/stdc++.h> 
using namespace std; // node data type 
struct Node { Node* left; Node* right; int hd; int data; 
}; // utility function to create new node 
Node* newNode(int key) 
{ Node* node = new Node(); node->left = node->right = NULL; node->data = key; return node; 
} // function to print top view of a binary tree 
void topView(Node* root) 
{ if (root == NULL) { return; } queue<Node*> q; map<int, int> m; int hd = 0; root->hd = hd; q.push(root); while (q.size()) { hd = root->hd; if (m.count(hd) == 0) m[hd] = root->data; if (root->left) { root->left->hd = hd - 1; q.push(root->left); } if (root->right) { root->right->hd = hd + 1; q.push(root->right); } q.pop(); root = q.front(); } // printing top view for (auto i = m.begin(); i != m.end(); i++) { cout << i->second << " "; } 
} // Driver code 
int main() 
{ // new binary tree Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->right = newNode(5); topView(root); return 0; 
}

输出

4 2 1 3 5 

97. 编写程序打印二叉树的仰视图

// C++ program for bottom view of a binary tree 
#include <bits/stdc++.h> 
using namespace std; // node data type 
struct Node { Node* left; Node* right; int data; int hd; 
}; // utility function for new node 
Node* newNode(int key) 
{ Node* node = new Node(); node->data = key; node->left = node->right = NULL; node->hd = 0; return node; 
} // function to print bottom view 
void bottomView(Node* root) 
{ if (root == NULL) return; queue<Node*> q; map<int, int> m; int hd = 0; root->hd = hd; q.push(root); while (!q.empty()) { Node* temp = q.front(); q.pop(); hd = temp->hd; m[hd] = temp->data; if (temp->left != NULL) { temp->left->hd = hd - 1; q.push(temp->left); } if (temp->right != NULL) { temp->right->hd = hd + 1; q.push(temp->right); } } // printing top view for (auto i = m.begin(); i != m.end(); ++i) cout << i->second << " "; 
} // Driver Code 
int main() 
{ Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->right = newNode(5); bottomView(root); return 0; 
}

输出

4 2 1 3 5 

98. 编写程序打印二叉树的左视图

// C++ program to print left view of a binary tree 
#include <bits/stdc++.h> 
using namespace std; // node datatype 
struct Node { Node* left; Node* right; int data; 
}; // utility function to create a new node 
Node* newNode(int key) 
{ Node* node = new Node; node->data = key; node->left = node->right = NULL; return node; 
} // function to print left view 
void leftView(Node* root) 
{ if (!root) { return; } queue<Node*> q; q.push(root); while (!q.empty()) { int n = q.size(); for (int i = 1; i <= n; i++) { Node* temp = q.front(); q.pop(); if (i == 1) cout << temp->data << " "; if (temp->left != NULL) q.push(temp->left); if (temp->right != NULL) q.push(temp->right); } } 
} // Driver code 
int main() 
{ Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->right = newNode(5); leftView(root); 
}

输出

1 2 4 

99. 编写程序打印二叉树的右视图

// C++ program to print the right view of a binary tree 
#include <bits/stdc++.h> 
using namespace std; // node data type 
struct Node { Node* left; Node* right; int data; 
}; // utility function to create new node 
Node* newNode(int key) 
{ Node* node = new Node; node->data = key; node->left = node->right = NULL; return node; 
} // function to print right view of a binary tree 
void rightView(Node* root) 
{ if (root == NULL) { return; } queue<Node*> q; q.push(root); while (!q.empty()) { int n = q.size(); while (n--) { Node* x = q.front(); q.pop(); if (n == 0) { cout << x->data << " "; } if (x->left) { q.push(x->left); } if (x->right) { q.push(x->right); } } } 
} // Driver code 
int main() 
{ Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->right = newNode(5); rightView(root); 
}

输出

1 3 5 

100. 编写程序将中缀表达式转换为后缀表达式

// C++ program for infix expression to postfix expression 
// conversion 
#include <bits/stdc++.h> 
using namespace std; // infix to postfix conversion 
// supported operators => + - * / 
string infixToPostfix(string& expression) 
{ // string to store postfix expression string postfix; // operator stack stack<char> ope_stack; // operator precedence map unordered_map<char, int> pre = { { '+', 1 }, { '-', 1 }, { '*', 2 }, { '/', 2 }, { '(', 0 } }; int length = expression.length(); for (int i = 0; i < length; i++) { char c = expression[i]; // checking operands if ((c >= 92 && c <= 122) || (c >= 48 && c <= 57)) { postfix.push_back(c); } // checking braces else if (c == '(') { ope_stack.push(c); } else if (c == ')') { while (ope_stack.top() != '(') { postfix.push_back(ope_stack.top()); ope_stack.pop(); } ope_stack.pop(); } // checking operators else { while (!ope_stack.empty() && pre.at(c) < pre.at(ope_stack.top())) { postfix.push_back(ope_stack.top()); ope_stack.pop(); } ope_stack.push(c); } } // popping whole stack at the end while (!ope_stack.empty()) { postfix.push_back(ope_stack.top()); ope_stack.pop(); } return postfix; 
} // driver code 
int main() 
{ string s = "a*b+(c-d)"; cout << infixToPostfix(s); return 0; 
}

输出

ab*cd-+