Given a linked list, swap every two adjacent nodes and return its head.
Example:
Given1->2->3->4, you should return the list as2->1->4->3.
Note:
AC code:
/**
* 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) {
ListNode **dummy = &head, *a, *b;
while ((a=*dummy) && (b=a->next)) {
a->next = b->next;
b->next = a;
*dummy = b;
dummy = &(a->next);
}
return head;
}
};
Runtime: 0 ms, faster than 100.00% of C++ online submissions for Swap Nodes in Pairs.
1 2 3 4 5 6 a b 3 1 *pp pp->2->1-> a b (b)(a) 4 3 *pp *pp pp->4->3-> a b (b)(a) 5 4 *pp *pp pp->6->5 a b (b)(a) 6 5 *pp *pp
原文：https://www.cnblogs.com/ruruozhenhao/p/9746036.html