leetcode - 矩阵区域和

我来更新 leetcode 题目了，接着上一次，这一次是上一道题目的提升（有点数学题的感觉）

142.环形链表2

代码

struct ListNode *detectCycle(struct ListNode *head) 
{
    struct ListNode *slow = head;
    struct ListNode *fast = head;
    while(fast && fast->next)
    {
        slow = slow->next;
        fast = fast->next->next;
        if(slow == fast)
        {
               struct ListNode *meet = slow;
               slow = head;
               while(1)
             {
              if(meet == slow)
              {
                return meet;
              }
              else
              {
                meet = meet->next;
                slow = slow->next;
              }
            }
        }
    }
    return NULL;
}