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Curated lists

Pick a practice path

75 problems

Warm-Up

Build momentum while sharpening the fundamentals.

0/75 solved

120 problems

Interview Core

Carefully selected problems covering essential interview patterns.

0/120 solved

120 problems

Advanced Track

Demanding challenges that push your algorithmic reasoning further.

0/120 solved

20 problems

Premium Track

Premium problems with solutions for deeper preparation.

0/20 solved

TopicType

Difficulty

Status

404 results across 20 topics

Arrays & Hashing

0/36 solved

Easy: 21Medium: 14Hard: 1

Solution

Build Array from Permutation

Easy

Check If All 1's Are at Least Length K Places Away

Easy

Count Complete Subarrays in an Array

Medium

Count Covered Buildings

Medium

Count Elements With Maximum Frequency

Easy

Count Good Triplets

Easy

Count Special Triplets

Medium

Count Submatrices with Top-Left Element and Sum Less Than k

Medium

Divide an Array Into Subarrays With Minimum Cost I

Easy

Equal Sum Grid Partition I

Medium

Equal Sum Grid Partition II

Hard

Find All K-Distant Indices in an Array

Easy

Find Lucky Integer in an Array

Easy

Increment Submatrices by One

Medium

Longest Balanced Subarray I

Medium

Longest Harmonious Subsequence

Easy

Longest Subarray With Maximum Bitwise AND

Medium

Make Array Elements Equal to Zero

Easy

Maximum Difference Between Adjacent Elements in a Circular Array

Easy

Maximum Difference Between Increasing Elements

Easy

Maximum Side Length of a Square with Sum Less than or Equal to Threshold

Medium

Maximum Value of an Ordered Triplet I

Easy

Maximum Value of an Ordered Triplet II

Medium

Minimum Absolute Distance Between Mirror Pairs

Medium

Minimum Distance Between Three Equal Elements I

Easy

Minimum Distance Between Three Equal Elements II

Medium

Minimum Distance to the Target Element

Easy

N-Repeated Element in Size 2N Array

Easy

Number of Equivalent Domino Pairs

Easy

Special Positions in a Binary Matrix

Easy

The Two Sneaky Numbers of Digitville

Easy

Three Consecutive Odds

Easy

Transformed Array

Easy

Trionic Array I

Easy

Valid Sudoku

Medium

Zero Array Transformation I

Medium

Two Pointers

0/20 solved

Easy: 6Medium: 12Hard: 2

Solution

Adjacent Increasing Subarrays Detection I

Easy

Container With Most Water

Medium

Count and Say

Medium

Count Collisions on a Road

Medium

Count Hills and Valleys in an Array

Easy

Count Negative Numbers in a Sorted Matrix

Easy

Count the Number of Fair Pairs

Medium

Determine Whether Matrix Can Be Obtained By Rotation

Easy

Flip Square Submatrix Vertically

Easy

Maximum Distance Between a Pair of Values

Medium

Maximum Matching of Players With Trainers

Medium

Maximum Total Damage With Spell Casting

Medium

Minimize Maximum Pair Sum in Array

Medium

Minimum Time to Make Rope Colorful

Medium

Number of Smooth Descent Periods of a Stock

Medium

Number of Subsequences That Satisfy the Given Sum Condition

Medium

Number of Ways to Divide a Long Corridor

Hard

Trionic Array II

Hard

Two Furthest Houses With Different Colors

Easy

Valid Triangle Number

Medium

Sliding Window

0/26 solved

Easy: 4Medium: 13Hard: 9

Solution

Best Time to Buy and Sell Stock using Strategy

Medium

Check If a String Contains All Binary Codes of Size K

Medium

Count Partitions With Max-Min Difference at Most K

Medium

Count Subarrays of Length Three With a Condition

Easy

Count Subarrays Where Max Element Appears at Least K Times

Medium

Count Subarrays With Fixed Bounds

Hard

Count Subarrays With Score Less Than K

Hard

Count the Number of Good Subarrays

Medium

Divide an Array Into Subarrays With Minimum Cost II

Hard

Find X-Sum of All K-Long Subarrays I

Easy

Find X-Sum of All K-Long Subarrays II

Hard

Fruit Into Baskets

Medium

Largest 3-Same-Digit Number in String

Easy

Longest Subarray of 1's After Deleting One Element

Medium

Maximize Subarrays After Removing One Conflicting Pair

Hard

Maximize the Minimum Powered City

Hard

Maximum Difference Between Even and Odd Frequency II

Hard

Maximum Erasure Value

Medium

Maximum Frequency of an Element After Performing Operations II

Hard

Maximum Fruits Harvested After at Most K Steps

Hard

Minimum Absolute Difference in Sliding Submatrix

Medium

Minimum Difference Between Highest and Lowest of K Scores

Easy

Minimum Number of Flips to Make the Binary String Alternating

Medium

Minimum Removals to Balance Array

Medium

New 21 Game

Medium

Reschedule Meetings for Maximum Free Time I

Medium

Stack

0/9 solved

Medium: 6Hard: 3

Solution

Count Submatrices With All Ones

Medium

Lexicographically Minimum String After Removing Stars

Medium

Maximal Rectangle

Hard

Maximum Score From Removing Substrings

Medium

Minimum Operations to Convert All Elements to Zero

Medium

Power Grid Maintenance

Medium

Replace Non-Coprime Numbers in Array

Hard

Robot Collisions

Hard

Using a Robot to Print the Lexicographically Smallest String

Medium

Binary Search

0/15 solved

Easy: 1Medium: 7Hard: 7

Solution

Avoid Flood in The City

Medium

Closest Equal Element Queries

Medium

Find Smallest Letter Greater Than Target

Easy

Kth Smallest Product of Two Sorted Arrays

Hard

Last Day Where You Can Still Cross

Hard

Maximize the Distance Between Points on a Square

Hard

Maximum Frequency of an Element After Performing Operations I

Medium

Maximum Number of Events That Can Be Attended II

Hard

Maximum Number of Tasks You Can Assign

Hard

Maximum Running Time of N Computers

Hard

Maximum Walls Destroyed by Robots

Hard

Minimize the Maximum Difference of Pairs

Medium

Next Greater Numerically Balanced Number

Medium

Separate Squares I

Medium

Successful Pairs of Spells and Potions

Medium

Linked List

0/3 solved

Easy: 1Medium: 1Hard: 1

Solution

Convert Binary Number in a Linked List to Integer

Easy

Delete Nodes From Linked List Present in Array

Medium

Minimum Pair Removal to Sort Array II

Hard

Trees

0/15 solved

Easy: 2Medium: 7Hard: 6

Solution

Balance a Binary Search Tree

Medium

Balanced Binary Tree

Easy

Fruits Into Baskets III

Medium

Longest Balanced Subarray II

Hard

Lowest Common Ancestor of Deepest Leaves

Medium

Maximize the Number of Target Nodes After Connecting Trees I

Medium

Maximize the Number of Target Nodes After Connecting Trees II

Hard

Maximum Level Sum of a Binary Tree

Medium

Maximum Number of K-Divisible Components

Hard

Maximum Product of Splitted Binary Tree

Medium

Maximum Profit from Trading Stocks with Discounts

Hard

Minimum Score After Removals on a Tree

Hard

Separate Squares II

Hard

Smallest Subtree with all the Deepest Nodes

Medium

Sum of Root To Leaf Binary Numbers

Easy

Heap / Priority Queue

0/13 solved

Medium: 8Hard: 5

Solution

Find Minimum Time to Reach Last Room I

Medium

Find Minimum Time to Reach Last Room II

Medium

Maximum Average Pass Ratio

Medium

Maximum Number of Events That Can Be Attended

Medium

Meeting Rooms III

Hard

Minimum Cost Path with Edge Reversals

Medium

Minimum Cost to Convert String I

Medium

Minimum Cost to Convert String II

Hard

Minimum Difference in Sums After Removal of Elements

Hard

Minimum Number of Seconds to Make Mountain Height Zero

Medium

Swim in Rising Water

Hard

Trapping Rain Water II

Hard

Two Best Non-Overlapping Events

Medium

Backtracking

0/8 solved

Easy: 1Medium: 4Hard: 3

Solution

24 Game

Hard

Count Number of Maximum Bitwise-OR Subsets

Medium

Find Unique Binary String

Medium

Longest Subsequence Repeated k Times

Hard

Pyramid Transition Matrix

Medium

Sum of All Subset XOR Totals

Easy

The Earliest and Latest Rounds Where Players Compete

Hard

The k-th Lexicographical String of All Happy Strings of Length n

Medium

Tries

0/3 solved

Medium: 1Hard: 2

Solution

Delete Duplicate Folders in System

Hard

K-th Smallest in Lexicographical Order

Hard

Lexicographical Numbers

Medium

Graphs

0/13 solved

Medium: 8Hard: 5

Solution

Check if There is a Valid Path in a Grid

Medium

Detect Cycles in 2D Grid

Medium

Find All People With Secret

Hard

Find Closest Node to Given Two Nodes

Medium

Largest Color Value in a Directed Graph

Hard

Length of Longest V-Shaped Diagonal Segment

Hard

Lexicographically Smallest Equivalent String

Medium

Lexicographically Smallest String After Applying Operations

Medium

Maximize Spanning Tree Stability with Upgrades

Hard

Maximum Candies You Can Get from Boxes

Hard

Minimize Hamming Distance After Swap Operations

Medium

Pacific Atlantic Water Flow

Medium

Snakes and Ladders

Medium

1-D Dynamic Programming

0/16 solved

Medium: 14Hard: 2

Solution

Adjacent Increasing Subarrays Detection II

Medium

Bitwise ORs of Subarrays

Medium

Delete Columns to Make Sorted III

Hard

Domino and Tromino Tiling

Medium

Find the Minimum Amount of Time to Brew Potions

Medium

Largest Divisible Subset

Medium

Longest Unequal Adjacent Groups Subsequence II

Medium

Maximum Subarray Sum With Length Divisible by K

Medium

Minimum Deletions to Make String Balanced

Medium

Number of People Aware of a Secret

Medium

Number of Ways to Paint N × 3 Grid

Hard

Partition Equal Subset Sum

Medium

Solving Questions With Brainpower

Medium

Taking Maximum Energy From the Mystic Dungeon

Medium

Total Characters in String After Transformations I

Medium

Ways to Express an Integer as Sum of Powers

Medium

2-D Dynamic Programming

0/25 solved

Easy: 1Medium: 12Hard: 12

Solution

Best Time to Buy and Sell Stock V

Medium

Champagne Tower

Medium

Count Number of Balanced Permutations

Hard

Count Square Submatrices with All Ones

Medium

Find All Possible Stable Binary Arrays I

Medium

Find All Possible Stable Binary Arrays II

Hard

Find Sum of Array Product of Magical Sequences

Hard

Find the Maximum Length of Valid Subsequence II

Medium

Find the Maximum Number of Fruits Collected

Hard

Find the Original Typed String II

Hard

Max Dot Product of Two Subsequences

Hard

Maximize the Number of Partitions After Operations

Hard

Maximum Amount of Money Robot Can Earn

Medium

Maximum Non Negative Product in a Matrix

Medium

Minimum ASCII Delete Sum for Two Strings

Medium

Minimum Cost Path with Teleportations

Hard

Minimum Distance to Type a Word Using Two Fingers

Hard

Minimum Score Triangulation of Polygon

Medium

Minimum Total Distance Traveled

Hard

Ones and Zeroes

Medium

Painting a Grid With Three Different Colors

Hard

Pascal's Triangle

Easy

Paths in Matrix Whose Sum Is Divisible by K

Hard

Soup Servings

Medium

Triangle

Medium

Greedy

0/39 solved

Easy: 7Medium: 24Hard: 8

Solution

Apple Redistribution into Boxes

Easy

Candy

Hard

Delete Columns to Make Sorted II

Medium

Divide Array Into Arrays With Max Difference

Medium

Find the Maximum Length of Valid Subsequence I

Medium

Find the Maximum Sum of Node Values

Hard

Find the String with LCP

Hard

Furthest Point From Origin

Easy

Greatest Sum Divisible by Three

Medium

Largest Perimeter Triangle

Easy

Largest Submatrix With Rearrangements

Medium

Lexicographically Smallest Generated String

Hard

Longest Binary Subsequence Less Than or Equal to K

Medium

Longest Palindrome by Concatenating Two Letter Words

Medium

Longest Unequal Adjacent Groups Subsequence I

Easy

Max Difference You Can Get From Changing an Integer

Medium

Maximize Happiness of Selected Children

Medium

Maximum 69 Number

Easy

Maximum Difference by Remapping a Digit

Easy

Maximum Manhattan Distance After K Changes

Medium

Maximum Matrix Sum

Medium

Maximum Number of Distinct Elements After Operations

Medium

Maximum Number of Operations to Move Ones to the End

Medium

Maximum Unique Subarray Sum After Deletion

Easy

Minimum Deletions to Make String K-Special

Medium

Minimum Domino Rotations For Equal Row

Medium

Minimum Equal Sum of Two Arrays After Replacing Zeros

Medium

Minimum Number of Increments on Subarrays to Form a Target Array

Hard

Minimum Number of People to Teach

Medium

Minimum Swaps to Arrange a Binary Grid

Medium

Partition Array Such That Maximum Difference Is K

Medium

Partitioning Into Minimum Number Of Deci-Binary Numbers

Medium

Rabbits in Forest

Medium

Rearranging Fruits

Hard

Reschedule Meetings for Maximum Free Time II

Medium

Set Intersection Size At Least Two

Hard

Smallest Missing Non-negative Integer After Operations

Medium

Special Binary String

Hard

Zero Array Transformation III

Medium

Math & Geometry

0/68 solved

Easy: 27Medium: 32Hard: 9

Solution

Add Binary

Easy

Alice and Bob Playing Flower Game

Medium

Binary Prefix Divisible By 5

Easy

Concatenation of Consecutive Binary Numbers

Medium

Construct Product Matrix

Medium

Convert Integer to the Sum of Two No-Zero Integers

Easy

Count Equal and Divisible Pairs in an Array

Easy

Count Good Numbers

Medium

Count Largest Group

Easy

Count Number of Trapezoids I

Medium

Count Number of Trapezoids II

Hard

Count Odd Numbers in an Interval Range

Easy

Count of Interesting Subarrays

Medium

Count Operations to Obtain Zero

Easy

Count Partitions with Even Sum Difference

Easy

Count Square Sum Triples

Easy

Count Symmetric Integers

Easy

Count the Hidden Sequences

Medium

Count the Number of Arrays with K Matching Adjacent Elements

Hard

Count the Number of Computer Unlocking Permutations

Medium

Distribute Candies Among Children II

Medium

Divisible and Non-divisible Sums Difference

Easy

Find Closest Person

Easy

Find Minimum Operations to Make All Elements Divisible by Three

Easy

Find N Unique Integers Sum up to Zero

Easy

Find the Largest Area of Square Inside Two Rectangles

Medium

Find the Minimum Area to Cover All Ones I

Medium

Find the Minimum Area to Cover All Ones II

Hard

Find the Number of Ways to Place People I

Medium

Find the Number of Ways to Place People II

Hard

Find Triangular Sum of an Array

Medium

Finding 3-Digit Even Numbers

Easy

Four Divisors

Medium

Fraction to Recurring Decimal

Medium

Get Biggest Three Rhombus Sums in a Grid

Medium

Largest Magic Square

Medium

Largest Triangle Area

Easy

Magic Squares In Grid

Medium

Make Sum Divisible by P

Medium

Maximize Area of Square Hole in Grid

Medium

Maximum Area of Longest Diagonal Rectangle

Easy

Maximum Square Area by Removing Fences From a Field

Medium

Minimum Number of Operations to Make All Array Elements Equal to 1

Medium

Minimum Operations to Equalize Binary String

Hard

Minimum Operations to Make a Uni-Value Grid

Medium

Minimum Operations to Make Array Elements Zero

Hard

Minimum Operations to Make Array Sum Divisible by K

Easy

Minimum Operations to Make the Integer Zero

Medium

Minimum Time Visiting All Points

Easy

Mirror Distance of an Integer

Easy

Number of Laser Beams in a Bank

Medium

Number of Substrings With Only 1s

Medium

Number of Zero-Filled Subarrays

Medium

Plus One

Easy

Power of Four

Easy

Power of Three

Easy

Prime Number of Set Bits in Binary Representation

Easy

Range Product Queries of Powers

Medium

Reordered Power of 2

Medium

Shortest Distance to Target String in a Circular Array

Easy

Smallest Integer Divisible by K

Medium

Sum of Distances

Medium

Sum of k-Mirror Numbers

Hard

Total Characters in String After Transformations II

Hard

Type of Triangle

Easy

Walking Robot Simulation

Medium

Water Bottles

Easy

XOR After Range Multiplication Queries II

Hard

Bit Manipulation

0/14 solved

Easy: 9Medium: 3Hard: 2

Solution

Binary Gap

Easy

Binary Number with Alternating Bits

Easy

Binary Watch

Easy

Complement of Base 10 Integer

Easy

Construct the Minimum Bitwise Array I

Easy

Construct the Minimum Bitwise Array II

Medium

Find the K-th Character in String Game II

Hard

Minimum One Bit Operations to Make Integers Zero

Hard

Power of Two

Easy

Reverse Bits

Easy

Smallest Number With All Set Bits

Easy

Smallest Subarrays With Maximum Bitwise OR

Medium

Sort Integers by The Number of 1 Bits

Easy

XOR After Range Multiplication Queries I

Medium

Design

0/29 solved

Easy: 10Medium: 17Hard: 2

Solution

Design a Campus Print Quota

Easy

Design a Checkpointed Score Ledger

Medium

Design a Color Mixing Notebook

Easy

Design a Cooldown Radio Queue

Medium

Design a Dynamic Triage Queue

Medium

Design a Focus Session Tracker

Medium

Design a Food Rating System

Medium

Design a Laundry Timer Board

Easy

Design a Neighborhood Tool Library

Medium

Design a Quiet Seat Board

Easy

Design a Quiet-Hours Monitor

Easy

Design a Quiz Answer Board

Easy

Design a Reading Streak Board

Medium

Design a Reusable Cup Station

Easy

Design a Round-Robin Workshop Queue

Medium

Design a Shared Umbrella Network

Easy

Design a Shelf-Life Pantry

Medium

Design a Shift Exchange Board

Medium

Design a Station Departure Board

Easy

Design a Whiteboard Layer Stack

Easy

Design an Announcement Digest

Medium

Design Movie Rental System

Hard

Design Spreadsheet

Medium

Design Task Manager

Medium

Fancy Sequence

Hard

Finding Pairs With a Certain Sum

Medium

Implement Router

Medium

Simple Bank System

Medium

Walking Robot Simulation II

Medium

Strings

0/38 solved

Easy: 20Medium: 18

Solution

Check if Binary String Has at Most One Segment of Ones

Easy

Check If Digits Are Equal in String After Operations I

Easy

Check if Strings Can be Made Equal With Operations I

Easy

Check if Strings Can be Made Equal With Operations II

Medium

Compare Version Numbers

Medium

Count Binary Substrings

Easy

Count Mentions Per User

Medium

Count Submatrices With Equal Frequency of X and Y

Medium

Count the Number of Substrings With Dominant Ones

Medium

Coupon Code Validator

Easy

Decode the Slanted Ciphertext

Medium

Delete Characters to Make Fancy String

Easy

Delete Columns to Make Sorted

Easy

Divide a String Into Groups of Size k

Easy

Final Value of Variable After Performing Operations

Easy

Find Most Frequent Vowel and Consonant

Easy

Find Numbers with Even Number of Digits

Easy

Find Resultant Array After Removing Anagrams

Easy

Find the K-th Character in String Game I

Easy

Find the Lexicographically Largest String From the Box I

Medium

Find the Original Typed String I

Easy

Find Words Containing Character

Easy

Longest Balanced Substring I

Medium

Longest Balanced Substring II

Medium

Maximum Difference Between Even and Odd Frequency I

Easy

Maximum Number of Words You Can Type

Easy

Minimum Changes To Make Alternating Binary String

Easy

Minimum Penalty for a Shop

Medium

Number of Steps to Reduce a Number in Binary Representation to One

Medium

Push Dominoes

Medium

Remove Sub-Folders from the Filesystem

Medium

Robot Return to Origin

Easy

Sort Vowels in a String

Medium

Unique Length-3 Palindromic Subsequences

Medium

Valid Word

Easy

Vowel Spellchecker

Medium

Vowels Game in a String

Medium

Words Within Two Edits of Dictionary

Medium

Simulation

0/10 solved

Easy: 7Medium: 3

Solution

1-bit and 2-bit Characters

Easy

Calculate Money in Impoldev Bank

Easy

Count Unguarded Cells in the Grid

Medium

Diagonal Traverse

Medium

Fruits Into Baskets II

Easy

Keep Multiplying Found Values by Two

Easy

Matrix Similarity After Cyclic Shifts

Easy

Minimum Number of Operations to Make Elements in Array Distinct

Easy

Minimum Pair Removal to Sort Array I

Easy

Water Bottles II

Medium

Sorting

0/4 solved

Easy: 3Medium: 1

Solution

Find Subsequence of Length K With the Largest Sum

Easy

Minimum Absolute Difference

Easy

Minimum Operations to Make Array Values Equal to K

Easy

Sort Matrix by Diagonals

Medium