Coding & Algorithms Interview Questions
Practice 3,469 real Coding & Algorithms interview questions for 2026. Covers companies like Meta, Amazon, Google, Uber, and Microsoft. Real questions from actual interviews with detailed solutions — ideal for focused interview preparation. Coding & Algorithms interview questions are the single most common technical gate for software engineering roles and are used to evaluate problem framing, algorithm selection, complexity trade-offs, correctness, edge-case reasoning, and clear communication under time pressure. Expect this category to appear in early technical screens and repeatedly across onsite loops at companies that weight it heavily (notably Meta, Google, and Amazon). Interviews will test arrays and strings, trees and graphs, dynamic programming, hashing and two‑pointer techniques, and the candidate’s ability to test and optimize code in a shared editor. Prepare with timed mock interviews, practice in the same editor you’ll use live, and build a progressive schedule that moves from fundamentals to medium/hard problems; typical candidates invest several weeks to a few months of focused practice depending on seniority and target company.
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"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"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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"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"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."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"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."
Generate Weighted Random NFTs with Updates
You manage k NFT types, each with a positive integer rarity weight w[i]. Implement a minter: constructor(w) builds any needed structures in O(k); mint...
Implement a Simple Banking Ledger
Design and implement a banking ledger for n accounts labeled 1..n with initial balances. Provide an API: deposit(id, amount) -> bool, withdraw(id, amo...
Merge two interval lists into a union
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Compute nested depth-weighted sum
You are given a nested structure containing integers and lists (e.g., [1, [4, [6]]]). Define depth of the top-level as 1. Compute the total sum of all...
Maximize optional tasks under daily limit
You are given an integer limit and two integer arrays required and optional of length n. For each day i, you must schedule required[i]. If time remain...
Count k for consecutive-sum generator
An array generator service produces a consecutive-integers array starting at a positive integer k: [k, k+1, ..., k+m−1] for some m ≥ 1. The service re...
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...
Find minimum covering substring
Given two strings s and t, return the shortest contiguous substring of s that contains every character of t with at least the same multiplicities. If ...
Count inversions in an array efficiently
Given the array [5, 7, 9, 2, 3, 12, 8, 4], compute the number of inversion pairs (i, j) where i < j and arr[i] > arr[j]. Describe both a naive O(n^ 2)...
Design a rolling five-minute hit counter
Design an in-memory hit counter that supports: ( 1) recordHit(timestamp) to log an event, and ( 2) getCountLast5Minutes(now) to return the number of e...
Implement hostname-restricted web crawler
Implement a single-threaded web crawler that, given a starting URL startUrl and an interface getUrls(url) that returns all hyperlinks on the page at u...
Solve grid min path and sqrt by binary search
1) Given an m x n matrix of non-negative integers, find a path from the top-left to the bottom-right that minimizes the sum of cell values. You may on...
Verify permutation in-place and implement fast power
1) Given an integer list A of length n, determine whether A is a permutation of [0, 1, ..., n-1]. Do it in-place with O( 1) extra space (no auxiliary ...
Implement single-tab browser history navigation
Implement a BrowserSession for a single-tab browser. APIs: - BrowserSession(string homepage): Initialize with homepage; current page starts at homepag...
Insert and merge an interval
You are given a list of pairwise non-overlapping closed intervals [si, ei] sorted by start time, and a new interval [s, e]. Insert [s, e] into the lis...
Detect cycle in a directed graph
Given a directed graph represented by an adjacency list with n vertices and m edges, determine whether the graph contains a cycle. Describe and implem...
Implement command-driven in-memory key-value database
Implement a command-driven in-memory key–value database. Supported commands (one per line): 1) SET key value 2) GET key → print value or NULL 3) DELET...
Implement string dedup and mirror tree traversal
- String cleanup with group deletions (LeetCode-inspired): Given a string s consisting of lowercase letters, repeatedly delete any maximal contiguous ...
Set second tree values by subtree sums
Given the roots of two complete binary trees T1 and T2 that have identical structure and the same number of nodes, replace each value in T2 with the s...
Search target in unknown-length sorted array
You have read-only access to a sorted, increasing array-like interface of unknown length that supports get(i), which returns a valid integer for in-bo...