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 {

    public ListNode EntryNodeOfLoop(ListNode pHead) {
        ListNode slow = pHead, fast = pHead;
        while(fast != null && fast.next != null){
            slow = slow.next;
            fast = fast.next.next;
            if(slow == fast){
                slow = pHead;
                while(slow != fast){
                    slow = slow.next;
                    fast = fast.next;
                }
                return slow;
            }
        }   
        return null;
    }
}

直接背下来，手撕的时候默写就完事了。