Coding & Algorithms Interview Questions
Practice 3,013 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."
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...
Determine minimal substitutions and removals
Question Given a list of words, determine the minimum number of character substitutions required so that, in every word, no two adjacent characters ar...
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:/...
Implement right side view and local minimum search
Question LeetCode 199. Binary Tree Right Side View — Given the root of a binary tree, return the values of the nodes you can see ordered from top to b...
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 ...
Find largest island area
Question Given a 2D grid of 0s and 1s, find the largest area of a connected group of 1s (island) using 4-directional adjacency; return that area. (Var...
Compare two string linked lists
Question Given two singly linked lists where each node stores one character as a string, determine whether the sequences of characters represented by ...
Solve diameter and shortest bridge problems
Question LeetCode 543. Diameter of Binary Tree LeetCode 934. Shortest Bridge https://leetcode.com/problems/diameter-of-binary-tree/description/ https:...
Determine Rounds for Star Substring Threshold
Question Given a string S, an offset array O (replacement order), and an integer M, repeatedly replace S[O[i]] with ''. Determine the minimum number o...
Solve LeetCode stack and tree problems
Question LeetCode 1249. Minimum Remove to Make Valid Parentheses LeetCode 863. All Nodes Distance K in Binary Tree https://leetcode.com/problems/minim...
Evaluate dependent variable expressions
Question Given a target variable name and a list of assignment strings of the form 'Ti = expression' where the expression is either a number, a single...
Find most frequent log user
Question You are given a list of log entries in string format, where each entry contains a username and an access timestamp separated by a delimiter (...
Round numeric string values
Question Given a numeric string, implement rounding to the nearest integer (e.g., '3.5' → '4', '100.01' → '100'). Follow-up: round to the last signifi...
Explain strings and copy complexity
Question What is a string? What fields does a struct string contain, and how would you implement it yourself? What is the time complexity of copying a...
Check Palindrome and Add Decimal Strings
Question LeetCode 266. Palindrome Permutation – Given a string, determine whether any permutation can form a palindrome. Follow-up: If a palindrome pe...
Convert bitmap into ASCII characters
Question Given an array/string of 0-1 bits representing a bitmap font, write code to render each character as a grid using '.' for 0 and '#' for 1, an...
Design Connect-N winner detector
Question Design a data structure for the Connect-N game: pieces are dropped into a column (occupying the lowest empty cell). Implement move(column, pl...
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...