24. Swap Nodes in Pairs

最新推荐文章于 2020-03-18 21:48:52 发布

原创最新推荐文章于 2020-03-18 21:48:52 发布 · 217 阅读

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本文介绍了一种链表中相邻节点的交换算法实现，通过递归方式改变节点指针指向来完成交换，而不修改节点值。该算法仅使用常数空间，并确保不改变列表中的数值。

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.

代码如下：

class Solution {
public:
	ListNode* swapPairs(ListNode* head) {
		if (head == NULL) return NULL;
		if (head->next == NULL) return head;
		ListNode *temp = new ListNode(head->val);
		temp->next = head->next->next;
		ListNode *p = head->next;	
		head->val = head->next->val;
		head->next = temp;
		head->next->next = swapPairs(head->next->next);
		delete p;
		p = NULL;
		return head;
	}
};