Is Palindrome Linked List easy or hard?

Palindrome Linked List is classified as an Easy problem on LeetCode. The array-based solution is straightforward, while the in-place reversal technique introduces intermediate-level linked list manipulation concepts.

Palindrome Linked List Python/Java solution

In Python or Java, the typical solution either copies node values into a list and applies a two-pointer check or reverses the second half of the linked list before comparing nodes. Both implementations run in O(n) time, with the optimal version using O(1) extra space.

How to solve Palindrome Linked List in O(n)?

Traverse the list with slow and fast pointers to locate the midpoint. Reverse the second half of the linked list in place, then compare nodes from the start and the reversed half one by one. If all values match, the list is a palindrome. The entire process takes linear time.

What is the best approach for Palindrome Linked List?

The most efficient approach reverses the second half of the linked list and compares it with the first half. This method runs in O(n) time and uses O(1) extra space. Interviewers prefer this approach because it demonstrates pointer manipulation and linked list reversal skills.

Is Palindrome Linked List asked at Google/Amazon/Meta?

Palindrome Linked List is a common interview question at companies like Amazon, Microsoft, and Meta because it tests linked list traversal, pointer manipulation, and in-place optimization. Variations also appear in technical screening rounds.

What data structure is used in Palindrome Linked List?

The problem primarily uses a singly linked list. Some solutions temporarily use an auxiliary array or stack to store node values, while the optimal approach relies on pointer techniques and in-place linked list reversal.

What is the time complexity of Palindrome Linked List?

The optimal solution runs in O(n) time because the list is traversed a constant number of times: once to find the middle, once to reverse the second half, and once to compare values. Simpler solutions using an array also run in O(n) time but require O(n) additional space.