Practice task library

Write code, query data, and review AI-generated implementations.

1,568Tasks in library

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Three quick classics. Run them right on the page, no account needed.

Two Sum

Easy · Find a pair

Valid Parentheses

Easy · Match brackets

Fizz Buzz

Easy · Use conditions

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All includes 8 projects without a difficulty level.

1–50 of 1568

Accuracy Score

Machine Learning

EasyMachine Learning

Actors and Directors

SQL · Aggregation

EasySQL · Aggregation

Add a backlog panel to the support dashboard

Agent oversight · 4 decisions · Sign in to practice

EasyAI agent oversight

Add a CSV export for invoices

Agent oversight · 4 decisions · Sign in to practice

EasyAI agent oversight

Add Binary

Bit Manipulation · String

EasyBit Manipulation · String

Add Digits

Math · Simulation

EasyMath · Simulation

Add health checks to the orders API pods

Agent oversight · 4 decisions · Sign in to practice

EasyAI agent oversight

Add Strings

Math · Simulation

EasyMath · Simulation

Add tags to the projects API

Agent oversight · 4 decisions · Sign in to practice

EasyAI agent oversight

Add to Array-Form of Integer

Array

EasyArray

Ads Performance

SQL · Aggregation

EasySQL · Aggregation

Agent patch applier for multi-hunk file edits

AI code review · Suggested 10–15 min · Sign in to practice

EasyAI engineering · Code review

Agent patch applier: path filter for proposed diffs

AI code review · Suggested 10–15 min · Sign in to practice

EasyAI engineering · Code review

Array Maximum

Array

EasyArray

Array Minimum

Array

EasyArray

Array Pair Sum

Array

EasyArray

Array Partition

Sorting · Array

EasySorting · Array

Article Views I

SQL

EasySQL

Assign Cookies

Greedy · Sorting

EasyGreedy · Sorting

Average of Levels in Binary Tree

Tree · Breadth-First Search

EasyTree · Breadth-First Search

Average Salary By Department

SQL · Sorting

EasySQL · Sorting

Backspace String Compare

Stack · String

EasyStack · String

Backward-Fill Nulls

Data Engineering · Array

EasyData Engineering · Array

Balanced Binary Tree

Tree

EasyTree

Base 7

Math · String

EasyMath · String

Baseball Game

Stack · Array

EasyStack · Array

Best Time to Buy and Sell Stock

Dynamic Programming · Array

EasyDynamic Programming · Array

Big Countries

SQL

EasySQL

Biggest Single Number

SQL · Aggregation

EasySQL · Aggregation

Binarize

Machine Learning · Array

EasyMachine Learning · Array

Binary Gap

Bit Manipulation

EasyBit Manipulation

Binary Search

Binary Search · Array

EasyBinary Search · Array

Binary Tree Paths

Tree · Backtracking

EasyTree · Backtracking

Binary Watch

Bit Manipulation · Backtracking

EasyBit Manipulation · Backtracking

Calculate Digit Sum of a String

Simulation · String

EasySimulation · String

Calculate Special Bonus

SQL

EasySQL

Can contact imports explain a file that is not UTF-8?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can digital-only orders check out without an address?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can Make Arithmetic Progression

Sorting · Array

EasySorting · Array

Can Make Arithmetic Progression From Sequence

Sorting · Array

EasySorting · Array

Can ops override port and debug from the environment?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can people open documents that were shared with them?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can Place Flowers

Greedy · Array

EasyGreedy · Array

Can pluralize include the count in notification text?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can product search filter to in-stock items?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can short dates drop the year for this year?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can sign-in errors say which part was mistyped?

PR review · Suggested 6 min · Sign in to practice

EasyCode review

Can team admins see their teammates' emails?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can the call log show long calls in hours?

PR review · Suggested 5 min · Sign in to practice

EasyCode review

Can the contact form explain why an email is invalid?

PR review · Suggested 6 min · Sign in to practice

EasyCode review

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