[LeetCode] Swap Nodes in Pairs

最新推荐文章于 2024-10-10 01:02:39 发布

原创最新推荐文章于 2024-10-10 01:02:39 发布 · 550 阅读

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本文介绍了一种算法，该算法能在常数空间内交换给定链表中的每两个相邻节点，例如将1->2->3->4转换为2->1->4->3。文章详细解释了如何仅通过改变节点指针来实现这一操作，而不修改节点中的实际值。

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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：

/**
 * 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* current = head;  
        ListNode* next = NULL;  
        ListNode* prev = NULL;  
        
        if(current)
        {
            next = current->next;
            current->next = prev;
            prev = current;
            current = next;
        }
        
        if(current)
        {
            next = current->next;
            current->next = prev;
            prev = current;
            current = next;
        }
        
        if(next)
            head->next = swapPairs(next);
        
        return prev;
    }
};