07月17日, 2015 1,078 views次
链接:https://leetcode.com/problems/swap-nodes-in-pairs/
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.
题意:给定一个链表,交换相邻的两个节点,交换节点而不是交换值
分析:用指针的指针来作交换,Python需要新建一个虚拟的首节点,用强大的C指针就方便多了,不过确实比较考验指针的应用能力啊。
CPP代码:
class Solution { public: ListNode* swapPairs(ListNode* head) { ListNode** cur = &head; while ((*cur) && (*cur)->next) { ListNode* t = (*cur)->next; (*cur)->next = (*cur)->next->next; t->next = *cur; *cur = t; cur = &(*cur)->next->next; } return head; } };
作弊CPP代码:
class Solution { public: ListNode* swapPairs(ListNode* head) { ListNode *p = head; while(p && p->next) { swap(p->val, p->next->val); p = p->next->next; } return head; } };