LeetCode#234. Palindrome Linked List

• 题目：判断一个链表是否为回文
• 难度：Easy
• 思路：
• 代码：

public class Solution {    public boolean isPalindrome(ListNode head) {        if(head == null || head.next == null){            return true;        }        int len = 0;        ListNode node = head;        while(node != null){            len++;            node = node.next;        }        int count = len/2-1;        ListNode pre = null;//指向前半部分的指针        ListNode curr = head;//指向后半部分的指针        ListNode next = curr.next;        while(count >= 0){            count--;            curr.next = pre;//反转前半部分的链表            pre = curr;            curr = next;            next = curr.next;        }        //如果链表长度为奇数，则后半部分的节点需要跳过第一个节点        if((len&1) == 1){            curr = next;        }        while(curr != null && pre != null){            if(curr.val != pre.val){                return false;            }            curr = curr.next;            pre = pre.next;        }        return true;    }}