Palindrome Linked List

Leetcode 234.

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/**
 * 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 == null || head.next == null)
          return true;
        ListNode slow = head, fast = head.next;
        while(fast != null && fast.next != null){
            slow = slow.next;
            fast = fast.next.next;
        }
        //avoid the even 
        if(fast != null)
         slow = slow.next;
         cut(head,slow);
     return  isPalindrome(head,reverseList(slow));
    }
    public boolean isPalindrome(ListNode l1,ListNode l2){
       while(l1 != null && l2 != null){
         if(l1.val != l2.val)
           return false;
        l1 = l1.next; 
        l2 = l2.next;
       }
    return true; 
    }
    public ListNode reverseList(ListNode head){
        if(head == null || head.next == null)
          return head; 
        ListNode temp = reverseList(head.next);
        head.next.next = head;
        head.next = null;

    return temp;
    }
    public void cut(ListNode l1, ListNode l2){
        while(l1.next != l2){
           l1 = l1.next;    
        }
        
     l1.next = null;
    }
}