/**
* 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) {
if(head.next==null){
return true;
}
Stack<ListNode> stk = new Stack<>();
ListNode slow = head;
ListNode fast = head;
while(fast!=null && fast.next!=null){
slow = slow.next;
fast=fast.next.next;
}
while(slow!=null){
stk.push(slow);
slow = slow.next;
}
while(!stk.isEmpty()){
if(head.val!=stk.pop().val){
return false;
}
head = head.next;
}
return true;
}
}/**
* 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) {
if(head.next==null){
return true;
}
Stack<ListNode> stk = new Stack<>();
ListNode slow = head;
ListNode fast = head;
while(fast.next!=null && fast.next.next!=null){
slow = slow.next;
fast=fast.next.next;
}
ListNode n2 = slow.next;//right first
slow.next = null;
ListNode n1 = null;
while(n2!=null){
ListNode temp = n2.next;
n2.next = n1;
n1 = n2;
n2 = temp;
}
boolean res = true;
while(n1!=null && head!=null){
if(n1.val!=head.val){
res = false;
break;
}
n1 = n1.next;
head = head.next;
}
return res;
}
}