https://leetcode.com/problems/swap-nodes-in-pairs/description/
题目
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.
题目翻译
题目解析
参考答案
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode *next;
* };
*/
struct ListNode* swapPairs(struct ListNode* head) {
if (NULL == head || NULL == head->next) {
return head;
}
struct ListNode * pCur;
struct ListNode * pNext;
struct ListNode * pLastTail;
pLastTail = head;
pCur = head;
pNext = pCur->next;
while (pCur != NULL && pNext != NULL)
{
pCur->next = pNext->next;
pNext->next = pCur;
if(pCur == head)
{
head = pNext;
}
else
{
pLastTail->next = pNext;
}
pLastTail = pCur;
pCur = pCur->next;
pNext = pCur != NULL ? pCur->next : NULL;
}
return head;
}
