题解 | #链表中环的入口结点#

import java.util.*;
/*
 public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}
*/
public class Solution {
//方法：快慢指针(代码随想录)
    public ListNode EntryNodeOfLoop(ListNode pHead) {
        ListNode fast=pHead;
        ListNode slow=pHead;
        while(fast!=null && fast.next !=null){
            fast=fast.next.next;
            slow=slow.next;
            if(slow == fast){
                ListNode index = pHead;
                while(slow != index){
                    slow=slow.next;
                    index = index.next;
                }
                return index;
            }
        }
        return null;
    }
}