首页 > itarticle > [leetcode] 24. swap nodes in pairs

[leetcode] 24. swap nodes in pairs

admin 11月 13, 2020 0

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.

标签：

Linked List

分析：

尝试不用虚头部解决这类链表问题～在正确性得到保证的情况下，尽可能地保持代码简洁。

代码：

class  {
public:
    ListNode* swapPairs(ListNode* head) {
        ListNode **hhead = &head;
        ListNode *a, *b;
        while ((a = *hhead) && (b = a->next)) {
            a->next = b->next;
            b->next = a;
            *hhead = b;

            hhead = &(a->next);
        }
        return head;
    }
};