package normal;

import java.util.HashSet;

/**
 * @program JavaBooks
 * @description: 141.环形链表
 * @author: mf
 * @create: 2019/11/05 10:19
 */

/*
题目：
难度：easy
类型：链表
 */
public class HasCycle {
    public static void main(String[] args) {

    }

    /**
     * 哈希
     * @param head
     * @return
     */
    public static boolean hasCycle(ListNode head) {
        HashSet<ListNode> set = new HashSet<>();
        while (head != null) {
            if (set.contains(head)) {