24. 两两交换链表中的节点

https://leetcode.cn/problems/swap-nodes-in-pairs/

思路

画图模拟一下过程

code

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* swapPairs(ListNode* head) {
        ListNode* dummyNode = new ListNode(0);
        dummyNode->next = head;
        ListNode* cur = dummyNode;
        while(cur->next&&cur->next->next){
            ListNode* tmp=cur->next; //记录临时节点
            ListNode* tmp1=cur->next->next->next; //记录临时节点

            cur->next =cur->next->next;
            cur->next->next=tmp;
            cur->next->next->next=tmp1;

            cur=cur->next->next;
        }
        return dummyNode->next;

    }
};
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