Coding & Algorithms Interview Questions
Practice 3,429 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."
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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."
"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."
Determine Maximum Path Length in Directed Acyclic Graph
Scenario A backend service represents task dependencies as a directed graph; you need to understand how deep the longest dependency chain can get. Que...
Calculate 95% Bootstrap Confidence Interval for Order Values
Scenario An e-commerce firm wants a 95% confidence interval for the average order value but only has a single historical sample of order amounts. Ques...
Implement BFS to Find Shortest Path in Graph
Scenario Social network needs to compute the shortest friend-distance between two users in an undirected graph containing millions of nodes. Question ...
Implement and Analyze 'Merge k Sorted Lists' Algorithm
Scenario Algorithm coding challenge during the final interview round. Question Implement LeetCode 23 ‘Merge k Sorted Lists’ and explain your complexit...
Design a Scalable, Fault-Tolerant Distributed Order System
Scenario Round covering distributed-system design and algorithm implementation. Question Design a highly available, low-latency distributed order-proc...
Optimal Stopping for Die Rolls That Bust on Perfect Squares
You repeatedly roll a fair six-sided die and keep a running cumulative sum $S$ of all the values rolled so far (starting from $S = 0$ before the first...
Find available reservation time slots
Problem You are building an API to show which time slots are available for booking at a restaurant. You are given: - The restaurant’s opening hours (p...
Optimize password transform and discount scheduling
Optimize password transform and discount scheduling Part 1 — Transform to palindromic k-periodic string: Input: a lowercase string currentPassword and...
Solve budget queries and shortest path
1) Budgeted purchases with sorted array: You are given an array prices of n positive integers and q budget queries. For each budget B, you may buy ite...
Parse Markdown Links Without Regex
Implement a function that converts simplified link syntax text into an HTML anchor tag <a href="url">text</a> across an entire input string. Constrain...
Compute longest palindromic subsequence
Given a string s (1 ≤ |s| ≤ 2000), implement a function that returns the length of the longest subsequence of s that reads the same forward and backwa...
Check carpool trip feasibility
You are given a list of trips where each trip i is (passengers_i, start_i, end_i) with start_i < end_i on a one-dimensional route. A single vehicle wi...
Parse a password from a matrix
Given an m x n matrix of characters, a starting coordinate (row, col), and a string of moves consisting of 'U', 'D', 'L', 'R', parse a password by vis...
Solve stock-pattern trading and substring elimination
Part A — Stock trading by pattern signals: - Input: an integer array prices (length n) of daily stock prices; an array buyPattern and an array sellPat...
Validate password strength and repair
Given a password policy—length between 8 and 20 characters; must include at least one lowercase letter, one uppercase letter, and one digit; and must ...
Design payment scheduler with cancel and top-K outgoing
Design and implement an in-memory banking payment component with the following APIs: ( 1) schedulePayment(payerId, payeeId, amount, executeAt) -> paym...
Design O(nm) grouping of rearranged strings
Given an array of strings, group together words that are permutations of the same characters. Provide a baseline solution that sorts each word (O(n · ...
Design time-versioned KV without timestamp argument
Design a time-versioned key-value store that does not accept a timestamp argument on writes. Support set(key, value) which stores the value with an in...
Implement binary search from scratch
Question Implement binary search on a sorted integer array without using any library helpers (no bisect, Arrays.binarySearch, etc.). Provide both iter...
Implement zigzag level-order traversal
Given the root of a binary tree, return the node values in zigzag level order: visit nodes level by level, reading the first level from left to right,...