Practice Problems

Each problem teaches a transferable pattern — the kind that shows up again and again in technical interviews at top companies.

15problems

11patterns covered

30+companies represented

Free Starter — 5 problems

1.Two Sum
GoogleAmazonMeta
Hash MapEasy
2.Contains Duplicate
AmazonAppleGoogle
SetEasy
3.Valid Anagram
GoogleAmazonMeta
Frequency MapEasy
4.Valid Palindrome
MetaMicrosoftAmazon
Two PointersEasy
5.Valid Parentheses
GoogleAmazonMeta
StackEasy

Early Access — 10 problems

$10 one-time

6.Best Time to Buy and Sell Stock
AmazonGoldman SachsGoogle
Tracking MinimumEasy🔒
7.Merge Two Sorted Lists
GoogleAmazonMicrosoft
Linked ListEasy🔒
8.Binary Search
GoogleAmazonMeta
Binary SearchEasy🔒
9.Search Insert Position
GoogleAmazon
Binary SearchEasy🔒
10.Move Zeroes
MetaGoogleAmazon
Two PointersEasy🔒
11.Maximum Subarray
AmazonGoogleApple
Kadane's AlgorithmMedium🔒
12.Longest Substring Without Repeating Characters
AmazonGoogleBloomberg
Sliding WindowMedium🔒
13.Maximum Average Subarray I
AmazonGoogle
Sliding WindowEasy🔒
14.Min Stack
AmazonGoogleBloomberg
StackMedium🔒
15.Invert Binary Tree
GoogleAmazonApple
Tree TraversalEasy🔒

Unlock 10 more problems

Pay once and the full problem set is yours — permanently. Every new problem we ship during early access is included automatically. No subscription, no upgrades, no catching up later.

Sliding WindowBinary SearchLinked ListKadane'sTree Traversal

$10one-time · yours forever