algorithm/Week_01/id_145/LeetCode_24_145.cpp at master · feixiangcode/algorithm · GitHub

37 lines (36 loc) · 881 Bytes

/**

* Definition for singly-linked list.

* struct ListNode {

* int val;

* ListNode *next;

* ListNode(int x) : val(x), next(NULL) {}

* };

class Solution {

public:

ListNode* swapPairs(ListNode* head) {

if(head == NULL||head->next == NULL)

return head;

ListNode *pre = head;

ListNode *temp = pre->next;

ListNode *resHead = temp;

ListNode *link = head;

while(temp!=NULL){

pre->next = temp->next;

temp->next = pre;

pre = pre->next;

if(pre == NULL){

break;

}

temp = pre->next;

if(temp!=NULL){

link->next = temp;

link = pre;

}else{

link->next = pre;

break;

}

return resHead;

}

};

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