leetcode-top100链表专题二

21.合并两个有序链表

题目链接

21. 合并两个有序链表 - 力扣（LeetCode）

解题代码

class Solution:def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:if not l1: return l2  # 终止条件，直到两个链表都空if not l2: return l1if l1.val <= l2.val:  # 递归调用l1.next = self.mergeTwoLists(l1.next,l2)return l1else:l2.next = self.mergeTwoLists(l1,l2.next)return l2

2.两数相加

题目链接

2. 两数相加 - 力扣（LeetCode）

解题思路

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:if not l1: return l2if not l2: return l1l1.val += l2.valif l1.val >= 10:l1.next = self.addTwoNumbers(ListNode(l1.val // 10),l1.next)l1.val %= 10l1.next = self.addTwoNumbers(l1.next,l2.next)return l1