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.
1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * struct ListNode *next; 6 * }; 7 */ 8 struct ListNode* swapPairs(struct ListNode* head) { 9 struct ListNode* p1; 10 struct ListNode* p2; 11 struct ListNode* tmp; 12 if (!head || !(head->next)){ 13 return head; 14 } 15 16 p1 = head; 17 p2 = p1->next; 18 19 tmp = p2->next; 20 head = p2; 21 p2->next = p1; 22 p1->next = swapPairs(tmp); 23 24 return head; 25 }
[LeetCode] 24. Swap Nodes in Pairs
原文：http://www.cnblogs.com/amadis/p/6032276.html