leetcode: Swap Nodes in Pairs (C++)_leetcode swap nodes in pairs c++-优快云博客

本文链接：https://blog.youkuaiyun.com/wubin91/article/details/38896735

本文介绍了一种链表中相邻节点交换的算法实现，包括基本思路和代码解析。

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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.

基本实现思路是设置三个滑动指针 t, p, q 对 ListNode 进行 swap 操作。

<span style="color:#333333;">/**
 * 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 *t = new ListNode(0); </span><span style="color:#009900;">//设置相邻的 3 个指针 t, p, q</span><span style="color:#333333;">
        t->next = head;
        ListNode *p = head;
        ListNode *q = head->next;
        head = q;
        while(1) {
            t->next = q;
            p->next = q->next;
            q->next = p;
            if(p->next == NULL || p->next->next == NULL) break;
            t = p;
            p = p->next;
            q = p->next;
        }
        return head;
    }
};</span>