LeetCode: Swap Nodes in Pairs

最新推荐文章于 2024-10-10 01:02:39 发布

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#leetcode #list #Swap Nodes in Pairs

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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。文章详细解释了实现这一操作的具体步骤，并提供了完整的C语言代码示例。

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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.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* swapPairs(struct ListNode* head) {
    if (head == NULL) return head;
    
    struct ListNode* curr = head;
    struct ListNode* nt = curr->next;
    if (nt == NULL) return head;
    struct ListNode* nh = (struct LsitNode*) malloc(sizeof(struct ListNode));
    
    struct ListNode* prev = nh;
    while(nt != NULL) {
        struct ListNode* tmp = nt->next;
        nt->next = curr;
        curr->next = tmp;
        prev->next = nt;
        prev = curr;
        curr = curr->next;
        if (curr != NULL) nt = curr->next;
        else break;
    }
    
    return nh->next;
    
}