01 二分查找的前提

02 binary_search函数

#include<bits/stdc++.h>
using namespace std;
int main(){vector<int> numbers={1,3,5,7,9};int target = 5;//使用binary_search 查找目标元素bool found = binary_search(numbers.begin(),numbers.end(),target);if(found){cout<<"Target element"<< target<<" found."<<endl;}else{ cout<<"Target element"<<target<<" not found."<<endl;}return 0;
}

03 lower_bound和upper_bound函数

#include<bits/stdc++.h>
using namespace std;
int main(){vector<int> v={5,1,7,3,10,18,9};sort(v.begin(),v.end());for(auto&i:v)cout<<i<<' ';cout<<'\n';//找到数组中第一个大于等于8的元素的位置cout<<(lower_bound(v.begin(),v.end(),8)-v.begin())<<'\n'; return 0;
}

04 例题讲解

https://www.lanqiao.cn/problems/1389/learning/?page=1&first_category_id=1&problem_id=1389

#include <iostream>
using namespace std;
int main()
{int i;int data[200];for(i=0;i<200;i++)data[i]=4*i+6;int target;cin>>target;for(i=0;i<200;i++){if(target==data[i]){cout<<i;break;}}return 0;
}