Coding & Algorithms Interview Questions
Practice 2,960 real Coding & Algorithms interview questions for 2026. Coding & Algorithms interview questions for top tech firms like Meta, Amazon, Google, Uber, and TikTok — real questions from actual interviews with detailed solutions — to power your interview preparation. This collection is sharply focused on algorithmic patterns (arrays, strings, sliding windows, trees/graphs, dynamic programming, greedy, two-pointers, and hashing), clean, review-ready code, and the explanation skills that distinguish hires. In 2026 expect familiar medium-to-hard problems plus newer twists: AI-enabled or multi-file coding rounds at some companies, more emphasis on explainability and edge-case reasoning, and occasional real-world performance constraints (streaming, concurrency, memory limits). Interviewers evaluate problem framing, algorithm choice, complexity trade-offs, test-case thinking, and communication under time pressure. Best prep mixes pattern-based practice, timed mock interviews, code-review style polishing, and rehearsed explanations of complexity and tradeoffs. Focus your last-mile prep on writing correct, readable code quickly and on explaining why your solution is robust and efficient for production scenarios.

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"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."
Solve 4 LeetCode algorithm problems
Question LeetCode 636. Exclusive Time of Functions LeetCode 253. Meeting Rooms II LeetCode 314. Binary Tree Vertical Order Traversal LeetCode 215. Kth...
Compute concurrent online drivers
Question Given each driver’s chronologically sorted delivery records, build an algorithm that, for a timestamp t, returns how many distinct drivers we...
Implement thread-safe blocking queue
Question Design and implement a thread-safe bounded blocking queue that supports concurrent enqueue and dequeue operations using standard synchronizat...
Find integer in most intervals
Question Given N integer intervals [ai, bi] (positive integers), find an integer that belongs to the maximum number of intervals (return any such inte...
Find lowest common ancestor
Question LeetCode 236. Lowest Common Ancestor of a Binary Tree — Given a binary tree, find the lowest common ancestor (LCA) of two given nodes. Follow...
Handle cards, islands, Trie, median
Question LeetCode 914. X of a Kind in a Deck of Cards LeetCode 694. Number of Distinct Islands LeetCode 208. Implement Trie (Prefix Tree) LeetCode 295...
Detect shuffle-mode sequence
Question Given a playlist of distinct songs and two player modes—Random (each next song chosen independently and uniformly at random, with replacement...
Solve island and frequency problems
Question LeetCode 200. Number of Islands – given a 2D grid, count the number of connected islands of '1's using DFS/BFS/Union-Find. LeetCode 695. Max ...
Randomly partition array into k segments
Question Given a list of integers and an integer k representing the number of segments, write a function that randomly partitions the list into k non-...
Solve three LeetCode coding problems
Question LeetCode 1249. Minimum Remove to Make Valid Parentheses LeetCode 827. Making A Large Island LeetCode 199. Binary Tree Right Side View https:/...
Determine equality after limited swaps
Question LeetCode 1790. Check if One String Swap Can Make Strings Equal Follow-up: Given two strings, determine if they can become anagrams of each ot...
Solve Aptitude Test: Logical, Numerical, Verbal Reasoning
Scenario Pre-employment aptitude screen assessing logical, numerical and verbal reasoning within a strict time limit Question You have 15 minutes to s...
Decode and Explain Ambiguity in Compression Strings
Scenario Compression library that encodes an array as count-value pairs where value is one digit but count may be many digits. Question Implement deco...
Implement Sampling and Minimize Loss in Numerical Coding
Scenario Numerical coding challenges on sampling and loss minimization. Question a) Implement functions to sample from truncated normal distributions ...
Solve Python Challenges: Reverse String, Palindrome, Fibonacci, Unique List
Scenario Live coding round – four quick Python exercises Question Implement a function that reverses a string in-place. Write code that returns True i...
Implement DelayQueue with Idempotent Task Execution
Scenario Message broker offers DelayQueue where tasks execute at future timestamps, ensuring idempotency on duplicate IDs. Question Implement a delay ...
Determine If Two Strings Are Anagrams Efficiently
Scenario Backend service needs to verify whether two user-provided strings are anagrams for text-matching features. Question Implement a Python functi...
Solve Data Structure Challenges with Python Algorithms
Scenario You are given coding challenges in Python to manipulate simple data structures. Question Remove duplicates from a list of integers while pres...
Normalize Columns in Binomial Matrix Efficiently
Scenario Write code that creates a 100×100 matrix of Binomial(1, 0. 5) samples and normalizes each column so it sums to 1. Question Provide an efficie...
Automate Python Virtual Environment Setup on Linux Terminal
Scenario Shell script that automates Python virtual-environment setup on a Linux terminal during a tech interview Question Walk through the script lin...