142. 环形链表

qxwithlsy

于 2020-07-17 23:53:51 发布

阅读量100

点赞数

分类专栏： leetcode

本文链接：https://blog.youkuaiyun.com/qxwithlsy/article/details/107420497

版权

leetcode 专栏收录该内容

36 篇文章

订阅专栏

快慢指针，好像和之前的某道题相似

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode *detectCycle(struct ListNode *head) {
    // 快慢指针
    struct ListNode *fast=head;
    struct ListNode *low=head;
    struct ListNode *newlow=head;
    while(fast && low && fast->next && fast->next->next && low->next )
    {
        fast=fast->next->next;
        low=low->next;
        if(fast==low)
        {
            while(newlow && low)
            {
                if(newlow==low)
                {
                    return newlow;
                }
                newlow=newlow->next;
                low=low->next;
            }
        }
    }
    return NULL;
}