Problem Solving Mastery

Practice. Interview. Excel.

Structured learning paths designed to help you ace coding interviews through real-time AI simulations and instant feedback.

Bring Your Own Problem

Arrays

28 problems

Strings

13 problems

DP

17 problems

Trees

11 problems

Graphs

7 problems

Hash Tables

11 problems

Study Plans

Blind 75

Essential 75 LeetCode questions

Coming Soon

Blind 150

Comprehensive interview prep

Coming Soon

Exp 30

Exp 180

Master experimental questions

Best Time to Buy and Sell Stock

Easy

#Array#Dynamic Programming

Contains Duplicate

Easy

#Array#Hash Table#Sorting

Product of Array Except Self

Medium

#Array#Prefix Sum

Maximum Subarray

Medium

#Dynamic Programming#Array#Divide and Conquer+1

Valid Palindrome

Easy

#Two Pointers#String

3Sum

Medium

#Array#Two Pointers#Sorting

Container With Most Water

Medium

#Array#Two Pointers#Greedy+1

Longest Substring Without Repeating Characters

Medium

#Hash Table#String#Sliding Window

Longest Repeating Character Replacement

Medium

#Hash Table#String#Sliding Window

#10

Valid Parentheses

Easy

#String#Stack

#11

Search in Rotated Sorted Array

Medium

#Array#Binary Search

#12

Find Minimum in Rotated Sorted Array

Medium

#Array#Binary Search

#13

Maximum Product Subarray

Medium

#Array#Dynamic Programming

#14

Maximum Depth Of Binary Tree

Easy

#Trees#BFS#Tree#DFS

#15

Invert Binary Tree

Easy

#Trees#BFS#Tree#DFS

#16

Same Tree

Easy

#Trees#BFS#Tree#DFS

#17

Missing Number

Easy

#Binary_bitManipulation#Bit Manipulation#Array

#18

Counting Bits

Easy

#Binary_bitManipulation#Bit Manipulation#Dynamic Programming

#19

Reverse Linked List

Easy

#Linked List#LinkedList

#20

Merge Two Sorted Lists

Easy

#Linked List#LinkedList

#21

Reorder List

Medium

#Linked List#LinkedList

#22

Remove Nth Node From End Of List

Medium

#LinkedList#Two Pointers#Linked List

#23

Number Of Islands

Medium

#BFS#Graph#Union Find#DFS

#24

Merge Intervals

Medium

#Intervals#Array

#25

Non Overlapping Intervals

Medium

#Array#Intervals#Greedy

#26

Two Sum

Easy

#Array#Arrays#Hash Table

#27

Group Anagrams

Medium

#String#Hash Table

#28

Minimum Window Substring

Hard

#String#Sliding Window#Hash Table

#29

Valid Anagram

Easy

#String#Hash Table

#30

Longest Palindromic Substring

Medium

#String#Dynamic Programming

#31

Unique Paths

Medium

#DynamicProgramming#Dynamic Programming

#32

Combination Sum

Medium

#Array#Backtracking#DynamicProgramming

#33

Word Break

Medium

#Trie#String#DynamicProgramming#Dynamic Programming

#34

House Robber

Medium

#DynamicProgramming#Dynamic Programming

#35

Jump Game

Medium

#Dynamic Programming#Array#DynamicProgramming#Greedy

#36

Decode Ways

Medium

#String#DynamicProgramming#Dynamic Programming

#37

Climbing Stairs

Easy

#DynamicProgramming#Dynamic Programming

#38

Coin Change

Medium

#Array#DynamicProgramming#Dynamic Programming

#39

Spiral Matrix

Medium

#Array#matrix#Matrix

#40

Rotate Image

Medium

#Array#matrix#Matrix

#41

Merge k Sorted Lists

Hard

#Heap#Divide and Conquer#Linked List

#42

Validate Binary Search Tree

Medium

#BST#Tree#DFS

#43

Number Of 1 Bits

Easy

#Bit Manipulation

#44

Implement Trie Prefix Tree

Medium

#Design#Trie

#45

Longest Consecutive Sequence

Medium

#Array#Union Find#Hash Table

#46

Binary Tree Maximum Path Sum

Hard

#Dynamic Programming#Tree#DFS

#47

House Robber Ii

Medium

#Dynamic Programming

#48

Alien Dictionary

Hard

#Topological Sort#Graph

#49

Linked List Cycle

Easy

#Linked List#Two Pointers

#50

Insert Interval

Medium

#Intervals#Array

#51

Reverse Bits

Easy

#Bit Manipulation

#52

Binary Tree Level Order Traversal

Medium

#BFS#Tree

#53

Number Of Connected Components In An Undirected Graph

Medium

#BFS#Graph#Union Find#DFS

#54

Pacific Atlantic Water Flow

Medium

#BFS#Graph#DFS

#55

Clone Graph

Medium

#BFS#Graph#DFS

#56

Word Search Ii

Hard

#Backtracking#Trie#DFS

#57

Serialize And Deserialize Binary Tree

Hard

#BFS#Tree#Design#DFS

#58

Sum Of Two Integers

Medium

#Bit Manipulation

#59

Kth Smallest Element In A Bst

Medium

#BST#Tree#DFS

#60

Design Add And Search Words Data Structure

Medium

#Trie#Design#DFS

#61

Encode And Decode Strings

Medium

#String#Design

#62

Subtree Of Another Tree

Easy

#Tree#DFS

#63

Palindromic Substrings

Medium

#String#Dynamic Programming

#64

Lowest Common Ancestor Of A Binary Search Tree

Medium

#BST#Tree#DFS

#65

Graph Valid Tree

Medium

#BFS#Graph#Union Find#DFS

#66

Longest Increasing Subsequence

Medium

#Array#Binary Search#Dynamic Programming

#67

Word Search

Medium

#Array#Backtracking#DFS

#68

Construct Binary Tree From Preorder And Inorder Traversal

Medium

#Tree#DFS

#69

Set Matrix Zeroes

Medium

#Matrix#Array

#70

Course Schedule

Medium

#BFS#Topological Sort#Graph#DFS

#71

Meeting Rooms Ii

Medium

#Heap#Array#Intervals

#72

Top K Frequent Elements

Medium

#Heap#Array#Hash Table

#73

Meeting Rooms

Easy

#Intervals#Array

#74

Longest Common Subsequence

Medium

#String#Dynamic Programming

#75

Find Median from Data Stream

Hard

#Heap#Design

#76

Pair Sum

Easy

#Array#Hash Table#Two Pointers#Sorting#BYOP+1

#77

Pair Sum

Easy

#Array#Hash Table#Two Pointers#Sorting#BYOP+1

More coming soon

We are constantly adding new problems to our database.