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Grokking the Coding Interview Patterns in Python

Palindrome Linked List

Explore how to identify whether a linked list is a palindrome by using fast and slow pointers. This lesson guides you through implementing a solution that retains the original list structure, preparing you to tackle similar coding interview challenges efficiently.

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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.

Python
usercode > Solution.py
# Definition for a Linked List node

# class ListNode:

#     def __init__(self, val=0, next=None):

#         self.val = val

#         self.next = next

from ds_v1.LinkedList.LinkedList import ListNode

from LinkedListReversal import reverse_linked_list



def palindrome(head):



    # Replace this placeholder return statement with your code

    return False
Palindrome Linked List