判断单链表回文

class ListNode {
int val;
ListNode next;
ListNode(int x) {
val = x;
}
}

public class Solution {
public boolean isPalindrome(ListNode head) {
if(head == null || head.next == null){
return true;
}

ListNode reverseHead = new ListNode(head.val);
reverseHead.next = null;
ListNode curr = head.next;
ListNode nextNode;

int count = 0;
while (head != null){
count++;
head = head.next;
}

int n = count/2;
while (--n > 0){
nextNode = curr.next;
curr.next = reverseHead;
reverseHead = curr;
curr = nextNode;
}

if(count%2 == 1){
curr = curr.next;
}

while (curr != null){
if(curr.val != reverseHead.val){
return false;
}
curr = curr.next;
reverseHead = reverseHead.next;
}

return true;
}
public static void main(String[] args){
ListNode head = new ListNode(1);
ListNode one = new ListNode(2);
ListNode two = new ListNode(3);
ListNode three = new ListNode(2);
ListNode four = new ListNode(1);
head.next = one;
one.next = two;
two.next = three;
three.next = four;
four.next = null;
System.out.println(new Solution().isPalindrome(head));
}
}