Coding & Algorithms Interview Questions
Practice 3,469 real coding and algorithms interview questions reported from interviews at Meta, Amazon, Google, Uber and Microsoft. The mix follows what these loops actually ask: arrays and strings, hash maps, two pointers and sliding windows, binary search, linked lists, trees and graphs, BFS and DFS, recursion and backtracking, dynamic programming, heaps and priority queues, and the occasional design-a-data-structure round. Roughly four in five are rated medium, which is where most technical screens sit; 477 are hard and cluster in onsite loops. 3,033 of them open in a console where you can run your solution against the test cases in Python, Java, C++ or JavaScript. 2,712 come from Software Engineer interviews, with the rest from Machine Learning Engineer, Data Scientist and Data Engineer loops, and 404 were set as take-home projects rather than live sessions.
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"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
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"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
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"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Compute vertical order of a BST
Compute the vertical order traversal of a binary search tree. Define coordinates so the root is at column 0, row 0; the left child is (col−1, row+ 1) ...
Simulate views on an n-ary tree
Given a rooted, ordered n-ary tree (each node has a value and an ordered list of children), simulate an observer who starts at the bottom-left, moves ...
Justify choosing JavaScript for interviews
If given a choice of language, why would you choose JavaScript for front-end interview coding? Compare trade-offs versus TypeScript or Python regardin...
Detect runs and collapse a numeric grid
You are given an m x n grid of digits (0– 9). Phase 1: Find every horizontal or vertical run of length ≥ 3 consisting of the same digit. For each run,...
Find minimal property set in neighborhood
You are given a list of properties, each Property(id: int, neighborhood: string, capacity: int). Given a targetNeighborhood (string) and groupSize (in...
Count non-decreasing arrays by digit sums
You are given an array required_sums of length n. Count how many non-decreasing arrays result[1..n] of integers satisfy all of the following: ( 1) for...
Implement sorting and set intersection with input parsing
Write two functions and explain your approach in under two minutes after coding: (A) Sorting: Implement sort_numbers(nums: List[int]) -> List[int] tha...
Maintain k-th largest in a stream
Design and implement a class KthLargest that, given an integer k and an initial list of integers, supports: ( 1) KthLargest(k, nums): constructor; ( 2...
Compute minimal flips connecting two islands
Given an n x n binary grid of 0s (water) and 1s (land) containing exactly two disjoint islands (cells with 1 connected 4-directionally), return the mi...
Implement pagination and a time-versioned key-value store
Implement two coding tasks: 1) Transaction pagination: Given an in-memory collection of transaction records with fields (txn_id: string, user_id: stri...
Design top-K frequency structure
Design an in-memory data structure that supports: add(x) to observe an item, inc(x) to increment its frequency, dec(x) to decrement (deleting when zer...
Find longest substring with at most k distinct
Given a string s and an integer k, return the length of the longest contiguous substring that contains at most k distinct characters. Provide an O(n) ...
Compute discounted prices in a queue
Given an integer array prices where prices[i] is the price of the i-th item in a checkout line, apply the following rule: for each i, find the first j...
Schedule dependent services with layered startup
You are given N services and dependency pairs (u -> v) meaning u must start before v. 1) Produce a valid startup order if one exists; otherwise detect...
Check balanced parentheses with multiple bracket types
Given a string containing only parentheses '()', determine whether it is balanced. Follow-up: extend the solution to also support '[]' and '{}' with c...
Design variable-size LRU cache
Implement an in-memory cache with least-recently-used eviction where each entry has a variable size in bytes. The cache exposes set(key, value, size),...
Find top-k rated nodes via traversal
You are given a finite graph (directed or undirected) with n nodes and m edges. Each node u has an integer rating r[u]. Given a starting node s and an...
Maximize operations by removing target-sum pairs
Given an integer array nums and an integer T, in one operation you may remove two elements whose sum equals T. Return the maximum number of operations...
Implement a robust shell CLI
Implement a POSIX-compliant shell script invoked as ./script.sh <username> <path_of_file> that outputs a single line formatted as "<timestamp> <licens...
Check path in N-ary tree
Given the root of an N-ary tree and a sequence of integers path[0..k-1], determine whether there exists a path starting at the root whose node values ...