Solve palindrome and list tasks
Quick Overview
This question evaluates proficiency in string algorithms and linked list manipulation, specifically techniques for constructing the shortest palindrome by prepending characters and reordering singly linked lists by 1-based index parity.
Reddit
Mar 2, 2026, 12:00 AM
Machine Learning Engineer
Onsite
Coding & Algorithms
2
0
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You are asked to solve two coding problems.
-
Build the shortest palindrome by prepending characters
: Given a string
s, add characters only to the front of the string so that the final string is a palindrome. Return the shortest possible result. Aim for a solution better than checking every prefix naively. - Reorder a linked list by index parity : Given the head of a singly linked list, reorder the list so that all nodes at odd 1-based positions appear first, followed by all nodes at even 1-based positions . Preserve the relative order within the odd group and within the even group, and return the new head.
For both problems, explain the algorithm and analyze time and space complexity.