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Palindrome Linked List

Understand how to check if a linked list is a palindrome by leveraging fast and slow pointers while maintaining the list's original structure. This lesson teaches you to implement this efficiently, preparing you to solve related coding interview problems with confidence.

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Statement

Given the head of a linked list, your task is to check whether the linked list is a palindrome or not. Return TRUE if the linked list is a palindrome; otherwise, return FALSE.

Note: The original structure of the linked list must remain unchanged before and after the checking process.

Constraints:

Let n be the number of nodes in a linked list.

  • 1≤1\leq n ≤500\leq500

  • 0≤0 \leq Node.value ≤9\leq 9.

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Palindrome Linked List

1.

What is the output if the following linked list is provided as input?

7 → 3 → 3 → 3 → 7

A.

TRUE

B.

FALSE

1 / 4

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5
6

Try it yourself

Implement your solution in the following coding playground. We have also provided a useful code template that you may build on to solve this problem.

Java
usercode > Solution.java
// Definition for a Linked List node
// class ListNode {
//     int val;
//     ListNode next;
//     // Constructor
//     public ListNode(int val) {
//         this.val = val;
//         this.next = null;
//     }
// }
import ds_v1.LinkedList.ListNode;
import java.util.*;
public class Solution{
    public static boolean palindrome(ListNode head) {
      // Replace this placeholder return statement with your code
        return false;
    }
}
Palindrome Linked List