Coding Interview Questions

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638 questions
547 companies
27 roles
Last updated Nov 2026

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Write code that fits a linear regression by gradient descent.
10 months ago
Given two binary trees, decide whether the second appears as a subtree of the first (same structure and values from some node down). Then optimise your solution.
6 years ago
Given two lists of (timestamp, value) tuples representing time series, merge them into one time series represented as a list of tuples.
2 years ago
Implement malloc using an array: manage allocation and freeing of blocks inside a pre-defined array.
3 years ago
Given a chemical equation as a string of molecules with optional coefficients and element counts, decide whether it is balanced.
4 years ago
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Implement the move logic of the game 2048: slide and merge the tiles of a grid in each of the four directions.
5 years ago
In SQL, select the second largest entry within each category.
3 days ago
Sentence t is a subsequence of the words of sentence s. Matching t against s from left to right, return the words of s that are left unmatched, in order.
3 days ago
Determine whether an element is present in a matrix whose rows and columns are all sorted.
+33 days ago
Implement a lock-free single-producer single-consumer queue in C++.
3 days ago
Name the basic SQL keywords, then write a query that selects duplicate rows in a table.
3 days ago
Implement an object-pool allocator in which objects are allocated on one thread and freed on another.
3 days ago
Implement an in-memory order book for one instrument in C++, with add, cancel by order id, quantity at a level and depth from the best price.
3 days ago
Implement an order book with three functions: insert an order, delete an order, and return the total volume resting at a given price level.
10 months ago
Given an array of daily prices, find the maximum profit from at most two buy-then-sell transactions, holding at most one share at a time.
3 days ago
Design a fast, growable Array<T> whose elements never change address once created, where at(index) creates a zero-initialised element on first access.
2 years ago
Create a linked list. Then write a function that swaps the positions of two nodes in it.
5 years ago
Write a program that outputs the first n Ramanujan numbers: integers that are a sum of two positive cubes in at least two different ways, such as 1729.
4 years ago
Track matching brackets or code-block delimiters with a stack, then extend the solution into an editor that can collapse code blocks.
10 months ago
Write a function that decides whether a string is a palindrome.
3 days ago

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Coding Interview Questions

Write code that fits a linear regression by gradient descent.

Given two binary trees, decide whether the second appears as a subtree of the first (same structure and values from some node down). Then optimise your solution.

Given two lists of (timestamp, value) tuples representing time series, merge them into one time series represented as a list of tuples.

Implement malloc using an array: manage allocation and freeing of blocks inside a pre-defined array.

Given a chemical equation as a string of molecules with optional coefficients and element counts, decide whether it is balanced.

Implement the move logic of the game 2048: slide and merge the tiles of a grid in each of the four directions.

In SQL, select the second largest entry within each category.

Sentence t is a subsequence of the words of sentence s. Matching t against s from left to right, return the words of s that are left unmatched, in order.

Determine whether an element is present in a matrix whose rows and columns are all sorted.

Implement a lock-free single-producer single-consumer queue in C++.

Name the basic SQL keywords, then write a query that selects duplicate rows in a table.

Implement an object-pool allocator in which objects are allocated on one thread and freed on another.

Implement an in-memory order book for one instrument in C++, with add, cancel by order id, quantity at a level and depth from the best price.

Implement an order book with three functions: insert an order, delete an order, and return the total volume resting at a given price level.

Given an array of daily prices, find the maximum profit from at most two buy-then-sell transactions, holding at most one share at a time.

Design a fast, growable Array<T> whose elements never change address once created, where at(index) creates a zero-initialised element on first access.

Create a linked list. Then write a function that swaps the positions of two nodes in it.

Write a program that outputs the first n Ramanujan numbers: integers that are a sum of two positive cubes in at least two different ways, such as 1729.

Track matching brackets or code-block delimiters with a stack, then extend the solution into an editor that can collapse code blocks.

Write a function that decides whether a string is a palindrome.

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