Linear Coding Interview Questions
25 Linear coding interview problems with full optimal solutions — 8 easy, 12 medium, 5 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Linear interviewer values, and a FAQ section.
Showing 8 problems of 25
- #1easyfrequently asked
1. Two Sum
Find two numbers in an array that add to a target. Linear asks this as a warm-up to see if you reach for the O(n) hash-map solution immediately or stumble through O(n²) brute force first.
- #20easyfrequently asked
20. Valid Parentheses
Determine whether a string of brackets is balanced. Linear uses this to see if you naturally reach for a stack and can explain the push/pop invariant clearly — a proxy for how you communicate data-structure choices.
- #21easyfrequently asked
21. Merge Two Sorted Lists
Merge two sorted linked lists into one sorted list. Linear asks this as a foundational pointer problem — it directly primes the harder follow-up (Merge K Sorted Lists) and reveals whether you use a dummy head to simplify edge cases.
- #53easyfrequently asked
53. Maximum Subarray
Find the contiguous subarray with the largest sum. Linear uses this to see if you know Kadane's algorithm by name and can articulate the 'restart if running sum goes negative' intuition before writing a single line of code.
- #70easycommonly asked
70. Climbing Stairs
Count the number of distinct ways to climb n stairs taking 1 or 2 steps at a time. Linear asks this to see if you recognize it as Fibonacci DP and can articulate why memoization beats plain recursion — a proxy for how you think about repeated subproblems.
- #121easyfrequently asked
121. Best Time to Buy and Sell Stock
Find the maximum profit from a single buy-then-sell transaction. Linear uses this to see if you recognize the 'running minimum' pattern — iterating once while tracking the cheapest buy price seen so far.
- #206easyfrequently asked
206. Reverse Linked List
Reverse a singly-linked list. Linear uses this to probe pointer manipulation fundamentals and to see whether you can explain both the iterative and recursive versions — and articulate which is preferred in production.
- #704easycommonly asked
704. Binary Search
Search a sorted array in O(log n). Linear asks this to verify you can write a correct binary search without off-by-one bugs — a small problem that reveals a lot about coding precision.