Interview questions

Maximum Product of Three Numbers

Given an integer array, return the maximum product obtainable by multiplying any three numbers. Consider both the three largest values and the combination of the…

Companies: Salesforce

Array · Math · Sorting

Last reported Jun 2026

Number of Distinct Islands

Given a binary grid, count how many distinct island shapes (connected components of 1s via 4-directional adjacency) appear, treating two islands as identical if they…

Companies: Anduril, Oracle, TikTok

Array · Breadth-First Search · Depth-First Search · Hash Function

Last reported Jun 2026

Design Search Autocomplete System

Design an online autocomplete system that processes characters one-by-one, returning the top 3 historically most frequent sentences that match the current prefix (ranked by…

Companies: Google, Netflix, Pinterest, Vercel

Data Stream · Depth-First Search · Design · Heap (Priority Queue)

Last reported May 2026

Merge Sorted Array

Given two sorted arrays nums1 and nums2 and counts m and n (nums1 has length m+n with its last n slots free), merge the elements…

Companies: Amazon, Bloomberg, Google, Meta +2

Array · Sorting · Two Pointers

Last reported Apr 2026

Single-Threaded CPU

Given tasks with enqueue and processing times, return the order a single-threaded CPU will process them when it always picks the available task with the…

Companies: DoorDash, TikTok

Array · Heap (Priority Queue) · Sorting

Last reported Oct 2025

Sort Array By Parity

Partition the array so that all even numbers appear before all odd numbers, returning any arrangement that satisfies this; order within the even/odd groups doesn't…

Companies: Meta, Zoho

Array · Sorting · Two Pointers

Last reported Jan 2025

Reorganize String

Rearrange the characters of a string so that no two adjacent characters are the same, returning any valid permutation or "" if none exists. Key…

Companies: Amazon, D. E. Shaw, Tesla

Counting · Greedy · Hash Table · Heap (Priority Queue)

Last reported Jan 2025

Minimum Absolute Difference

Find all pairs of distinct integers that achieve the minimum absolute difference; the typical approach is to sort the array and collect adjacent pairs with…

Companies: Amazon, Walmart Labs

Array · Sorting

Last reported Nov 2024

Sort Colors

Reorder an array of values 0, 1, and 2 in-place so all 0s come first, then 1s, then 2s (the Dutch National Flag problem); aim…

Companies: Amazon, Google, Microsoft, Walmart Labs

Array · Bubble Sort · Quicksort · Sorting

Last reported Oct 2024

Contains Duplicate

Return true if any integer appears at least twice in the array and false if all elements are distinct. Array length can be up to…

Companies: Google, Meta

Array · Hash Table · Sorting

Last reported Oct 2024

Smallest String With Swaps

Given a string and allowed index swap pairs, view pairs as edges in a graph to find connected components where characters can be freely permuted…

Companies: Goldman Sachs, Google

Array · Breadth-First Search · Depth-First Search · Hash Table

Last reported Oct 2024

3Sum Closest

Given an integer array and a target, find three numbers whose sum is closest to the target (unique solution guaranteed) and return that sum. This…

Companies: Bloomberg

Array · Sorting · Two Pointers

4Sum

Find all unique quadruplets of distinct elements in an integer array whose values sum to a given target. Results must avoid duplicates (order irrelevant); with…

Companies: Oracle

Array · Sorting · Two Pointers

Advantage Shuffle

Given two equal-length arrays, permute nums1 to maximize the number of positions where nums1[i] > nums2[i]. This is a greedy matching problem: sort nums1 and…

Companies: Walmart Labs

Array · Greedy · Sorting · Two Pointers

Brace Expansion

Given a string with brace-enclosed comma-separated option groups and implicit concatenation (e.g., "{a,b}c{d,e}"), generate all unique strings formed by choosing one option…

Companies: Anduril

Backtracking · Breadth-First Search · Sorting · Stack

Heaters

Given positions of houses and heaters on a line, find the minimum uniform radius R such that every house is within distance R of some…

Companies: Anduril

Array · Binary Search · Sorting · Two Pointers

High Five

Given a list of (studentId, score) pairs, compute each student's average of their top five scores and return the results as (studentId, average) sorted by…

Companies: Goldman Sachs

Array · Hash Table · Heap (Priority Queue) · Sorting

Make Lexicographically Smallest Array by Swapping Elements

You may swap two indices iff their values differ by at most limit; compute the lexicographically smallest array obtainable by any sequence of such swaps…

Companies: Goldman Sachs, Uber

Array · Sorting · Union-Find

Maximize Sum of Weights after Edge Removals

Given a weighted tree, remove edges so that each node's degree in the remaining forest is at most k while maximizing the total weight of…

Companies: LinkedIn, Uber

Depth-First Search · Dynamic Programming · Sorting · Tree

Maximum Gap

Given an integer array, find the maximum difference between successive elements in its sorted order; if fewer than two elements return 0. The catch is…

Companies: Waymo

Array · Bucket Sort · Pigeonhole Principle · Radix Sort

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 Cost to Hire K Workers

Choose k workers and pay each proportional to quality while meeting their minimum wages; the group's cost equals (sum of selected qualities) * max(wage[i]/quality[i]) among…

Companies: Apple

Array · Greedy · Heap (Priority Queue) · Sorting