Interview questions

All Nodes Distance K in Binary Tree

Given a binary tree and a target node value, return all node values at distance K from the target. The challenge is to traverse both…

Companies: Amazon, Meta, Microsoft, TikTok

Binary Tree · Breadth-First Search · Depth-First Search · Hash Table

Last reported Mar 2026

Shortest Path in Binary Matrix

Given an n×n binary grid where 0s are open and 1s are blocked, return the length (number of cells) of the shortest 8-directionally connected path…

Companies: Amazon, Anduril, Meta

Array · Breadth-First Search · Matrix

Last reported Dec 2025

Possible Bipartition

Given n people and pairwise dislikes, determine whether the corresponding undirected graph is bipartite — i.e., whether you can 2-color all vertices (split into two…

Companies: LinkedIn, TikTok, Uber

Bipartite Graph · Breadth-First Search · Depth-First Search · Graph Coloring

Last reported Dec 2025

Amount of Time for Binary Tree to Be Infected

Given a binary tree and a start node, compute how many minutes it takes for an infection that spreads each minute to adjacent nodes (parent/children)…

Companies: Microsoft, Salesforce

Binary Tree · Breadth-First Search · Depth-First Search · Hash Table

Last reported Dec 2025

Find the Safest Path in a Grid

Compute each cell's Manhattan distance to the nearest thief, then find a path from (0,0) to (n-1,n-1) that maximizes the minimum of those distances along…

Companies: Google, Meta, Uber

Array · Binary Search · Breadth-First Search · Heap (Priority Queue)

Last reported May 2025

Remove Invalid Parentheses

Given a string containing letters and parentheses, remove the minimum number of parentheses to produce all distinct valid parentheses strings and return them. The core…

Companies: Meta

Backtracking · Breadth-First Search · String

Last reported May 2025

Contain Virus

Simulate days on an m×n grid where infected cells spread 4-directionally: each day identify all connected infected regions, compute for each the set of uninfected…

Companies: Flipkart, Uber

Array · Breadth-First Search · Depth-First Search · Matrix

Last reported Jan 2025

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

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

Distance to a Cycle in Undirected Graph

Given an undirected graph, return for every vertex the shortest distance to the nearest vertex that lies on any cycle. Key idea: identify cycle vertices…

Companies: Salesforce

Breadth-First Search · Depth-First Search · Graph Theory · Topological Sort

Minimize Malware Spread

Given an undirected graph and a set of initially infected nodes, choose one initial node to remove so that the eventual malware spread across connected…

Companies: Zomato

Array · Breadth-First Search · Depth-First Search · Graph Theory

Snakes and Ladders

Treat the boustrophedon-labeled board as a 1D graph of squares where from any square you can move 1–6 steps (dice roll), but landing on a…

Companies: Tesla

Array · Breadth-First Search · Matrix

Stepping Numbers

Find all integers in a given inclusive range whose adjacent digits differ by exactly 1 (stepping numbers), including single-digit and zero cases. Because the range…

Companies: eBay

Backtracking · Breadth-First Search · Math