[Leetcode]Swap Nodes in Pairs

Given a linked list, swap every two adjacent nodes and return its head.

For example,Given 1->2->3->4, you should return the list as 2->1->4->3.

Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.

这道题有点意思。主要是记住交换后上一个的父节点还没改变呢，所以用递归来做是比较容易处理的。

1 class Solution { 2 public: 3 ListNode *swapPairs(ListNode *head) { 4 if(head==NULL || head->next==NULL) 5 return head; 6 ListNode *temp = head->next; 7 ListNode *forward = temp->next; 8 head->next->next = head; 9 head->next=swapPairs(forward); 10 return temp; 11 } 12 };

 

转载于:https://www.cnblogs.com/desp/p/4345793.html

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