Interview questions

Subarray Product Less Than K

Count the number of contiguous subarrays of positive integers whose product is strictly less than k. Because all nums > 0, this is a sliding-window/two-pointer…

Companies: Apple

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Oct 2026

Max Consecutive Ones III

Find the maximum length of a contiguous subarray that can be made all 1s by flipping at most k zeros — equivalently, find the longest…

Companies: Amazon, D. E. Shaw, LinkedIn, Meta

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Sep 2026

Minimum Window Substring

Find the smallest substring of s that contains all characters of t (including duplicates), or return "" if none exists. This is typically solved with…

Companies: Amazon, LinkedIn, Lyft, Meta +2

Hash Table · Sliding Window · String

Last reported Sep 2026

Maximum Number of Occurrences of a Substring

Find the substring (overlaps allowed) that occurs most often in s among those with length between minSize and maxSize and at most maxLetters distinct characters…

Companies: Chewy, LinkedIn, Microsoft

Hash Table · Sliding Window · String

Last reported Aug 2026

Sliding Window Maximum

Given an integer array and a window size k, return the maximum value for each contiguous subarray (sliding window) as it moves one step to…

Companies: Amazon, Bloomberg, D. E. Shaw, Expedia +7

Array · Heap (Priority Queue) · Monotonic Queue · Queue

Last reported Jun 2026

Longest Substring with At Most K Distinct Characters

Given a string and an integer K, find the length of the longest substring that contains at most K distinct characters. This is typically solved…

Companies: LinkedIn, TikTok

Hash Table · Sliding Window · String

Last reported Apr 2026

Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

Find the length of the longest contiguous subarray whose maximum minus minimum is ≤ limit; the key challenge is maintaining the window's current min and…

Companies: MongoDB, Uber

Array · Heap (Priority Queue) · Monotonic Queue · Ordered Set

Last reported Apr 2026

Count Subarrays With Fixed Bounds

Count the number of contiguous subarrays whose minimum equals minK and maximum equals maxK. The main challenge is to efficiently (O(n)) scan the array, partitioning…

Companies: Adobe, Uber

Array · Monotonic Queue · Queue · Sliding Window

Last reported Apr 2026

Permutation in String

Check whether any substring of s2 of length |s1| is a permutation of s1 (i.e., has the same character multiset). The core challenge is to…

Companies: Apple, Meta

Hash Table · Sliding Window · String · Two Pointers

Last reported Mar 2026

Find All Anagrams in a String

Given strings s and p, return all start indices of substrings in s that are anagrams of p; the core challenge is to detect equal…

Companies: Amazon, Databricks, Microsoft

Hash Table · Sliding Window · String

Last reported Feb 2026

Longest Repeating Character Replacement

Find the length of the longest substring that can be turned into all the same letter by performing at most k character replacements; this is…

Companies: D. E. Shaw, Goldman Sachs, Meta, Microsoft +1

Hash Table · Sliding Window · String

Last reported Oct 2025

Minimum Size Subarray Sum

Find the length of the shortest contiguous subarray of positive integers whose sum is at least a given target (return 0 if none exists). This…

Companies: Bloomberg, Meta, Toast

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Aug 2025

Shortest Subarray with Sum at Least K

Find the length of the shortest contiguous subarray whose sum is at least k, or return -1 if none exists. Because nums can contain negative…

Companies: Meta

Array · Binary Search · Heap (Priority Queue) · Monotonic Queue

Last reported Jan 2025

Alternating Groups II

Given a circular binary array and integer k, count how many contiguous length-k segments are alternating (every adjacent pair within the segment differs). Because of…

Companies: eBay

Array · Sliding Window

Count Number of Nice Subarrays

Count the number of contiguous subarrays that contain exactly k odd numbers in an integer array. The core challenge is to do this in linear…

Companies: TikTok

Array · Hash Table · Math · Prefix Sum

Fruit Into Baskets

Given an array of fruit types where you can pick from a contiguous sequence while carrying at most two distinct types (two baskets), return the…

Companies: Adobe, Amazon, Meta, Salesforce

Array · Hash Table · Sliding Window

Longest Substring Of All Vowels in Order

Find the length of the longest contiguous substring made only of vowels that contains each of 'a','e','i','o','u' at least once and whose characters never decrease…

Companies: Rippling

Sliding Window · String

Maximum Number of Visible Points

Convert each point to its polar angle around your location (counting points at the exact location separately), sort these angles and handle the circular wrap…

Companies: Anduril

Array · Geometry · Math · Sliding Window

Minimum Operations to Reduce X to Zero

Remove elements from either end to make the sum of removed elements equal x; equivalently, find the longest contiguous subarray whose sum equals total(nums) -…

Companies: Bloomberg

Array · Binary Search · Hash Table · Prefix Sum

Minimum Removals to Balance Array

Given nums and k, remove the fewest elements so the remaining array has max ≤ k * min. Equivalently, find the largest subset of numbers…

Companies: Salesforce

Array · Binary Search · Sliding Window · Sorting