141. 环形链表

categories: [Blog,Algorithm]

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141. 环形链表

    public boolean hasCycle(ListNode head) {
        ListNode fast=head,slow = head;
        while(fast!=null && fast.next!=null){
            fast = fast.next.next;
            slow = slow.next;
            if (fast == slow){
                return true;
            }
        }
        return false;
    }

234. 回文链表

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public boolean isPalindrome(ListNode head) {
        Stack<Integer> stk =new Stack();
        if (null==head || null==head.next) return true;
        ListNode p = head;

        while (p != null) &#123;
            stk.push(p.val);
            p = p.next;
        &#125;
        while (head != null)&#123;
            if(head.val == stk.peek()) &#123;
                stk.pop();
            &#125; else return false;
            head = head.next;
        &#125;
        return true;
    &#125;

// 作者：wo-yao-chu-qu-luan-shuo
// 链接：https://leetcode-cn.com/problems/palindrome-linked-list/solution/hui-wen-lian-biao-fu-zhu-zhan-by-wo-yao-ab2uc/

&#125;