36.Valid Sudoku
MediumArrayHash TableMatrix64.9% acceptance26 companiesVideo
Medium · With video · 157 results
48.Rotate Image
MediumArrayMathMatrix80.7% acceptance36 companiesVideo
54.Spiral Matrix
MediumArrayMatrixSimulation58.2% acceptance49 companiesVideo
59.Spiral Matrix II
MediumArrayMatrixSimulation76.0% acceptance11 companiesVideo
63.Unique Paths II
MediumArrayDynamic ProgrammingMatrix44.9% acceptance9 companiesVideo
64.Minimum Path Sum
MediumArrayDynamic ProgrammingMatrix68.6% acceptance17 companiesVideo
73.Set Matrix Zeroes
MediumArrayHash TableMatrix63.8% acceptance22 companiesVideo
74.Search a 2D Matrix
MediumArrayBinary SearchMatrix54.4% acceptance19 companiesVideo
79.Word Search
MediumArrayBacktrackingMatrix48.2% acceptance36 companiesVideo
130.Surrounded Regions
MediumArrayBreadth-First SearchDepth-First Search46.1% acceptance12 companiesVideo
200.Number of Islands
MediumArrayBreadth-First SearchDepth-First Search65.2% acceptance86 companiesVideo
221.Maximal Square
MediumArrayDynamic ProgrammingMatrix50.7% acceptance28 companiesVideo
240.Search a 2D Matrix II
MediumArrayBinary SearchDivide and Conquer58.2% acceptance16 companiesVideo
286.Walls and Gates
MediumArrayBreadth-First SearchMatrix63.9% acceptance11 companiesPremium elsewhere, free hereVideo
289.Game of Life
MediumArrayMatrixSimulation73.0% acceptance15 companiesVideo
304.Range Sum Query 2D - Immutable
MediumArrayDesignMatrix59.2% acceptance10 companiesVideo
308.Range Sum Query 2D - Mutable
MediumArrayBinary Indexed TreeDesign46.0% acceptance3 companiesPremium elsewhere, free hereVideo
311.Sparse Matrix Multiplication
MediumArrayHash TableMatrix69.3% acceptance9 companiesPremium elsewhere, free hereVideo
348.Design Tic-Tac-Toe
MediumArrayDesignHash Table58.8% acceptance13 companiesPremium elsewhere, free hereVideo
361.Bomb Enemy
MediumArrayDynamic ProgrammingMatrix52.8% acceptance2 companiesPremium elsewhere, free hereVideo
378.Kth Smallest Element in a Sorted Matrix
MediumArrayBinary SearchHeap (Priority Queue)65.1% acceptance10 companiesVideo
417.Pacific Atlantic Water Flow
MediumArrayBreadth-First SearchDepth-First Search61.3% acceptance11 companiesVideo
419.Battleships in a Board
MediumArrayDepth-First SearchMatrix77.4% acceptance8 companiesVideo
427.Construct Quad Tree
MediumArrayDivide and ConquerMatrix78.8% acceptance8 companiesVideo
490.The Maze
MediumArrayBreadth-First SearchDepth-First Search60.4% acceptance13 companiesPremium elsewhere, free hereVideo
498.Diagonal Traverse
MediumArrayMatrixSimulation67.1% acceptance12 companiesVideo
505.The Maze II
MediumArrayBreadth-First SearchDepth-First Search55.0% acceptance5 companiesPremium elsewhere, free hereVideo
529.Minesweeper
MediumArrayBreadth-First SearchDepth-First Search68.7% acceptance9 companiesVideo
531.Lonely Pixel I
MediumArrayHash TableMatrix62.3% acceptance1 companyPremium elsewhere, free hereVideo
533.Lonely Pixel II
MediumArrayHash TableMatrix48.7% acceptance1 companyPremium elsewhere, free hereVideo
542.01 Matrix
MediumArrayBreadth-First SearchDynamic Programming54.7% acceptance14 companiesVideo
562.Longest Line of Consecutive One in Matrix
MediumArrayDynamic ProgrammingMatrix50.5% acceptance1 companyPremium elsewhere, free hereVideo
695.Max Area of Island
MediumArrayBreadth-First SearchDepth-First Search73.9% acceptance20 companiesVideo
723.Candy Crush
MediumArrayMatrixSimulation77.6% acceptance11 companiesPremium elsewhere, free hereVideo
750.Number Of Corner Rectangles
MediumArrayDynamic ProgrammingMath67.8% acceptance1 companyPremium elsewhere, free hereVideo
794.Valid Tic-Tac-Toe State
MediumArrayMatrix34.7% acceptance3 companiesVideo
807.Max Increase to Keep City Skyline
MediumArrayGreedyMatrix86.2% acceptance3 companiesVideo
835.Image Overlap
MediumArrayMatrix70.6% acceptance1 companyVideo
840.Magic Squares In Grid
MediumArrayHash TableMath55.1% acceptance5 companiesVideo
861.Score After Flipping Matrix
MediumArrayBit ManipulationGreedy80.3% acceptance3 companiesVideo
885.Spiral Matrix III
MediumArrayMatrixSimulation84.6% acceptance8 companiesVideo
909.Snakes and Ladders
MediumArrayBreadth-First SearchMatrix48.0% acceptance12 companiesVideo
931.Minimum Falling Path Sum
MediumArrayDynamic ProgrammingMatrix60.8% acceptance8 companiesVideo
934.Shortest Bridge
MediumArrayBreadth-First SearchDepth-First Search59.9% acceptance16 companiesVideo
959.Regions Cut By Slashes
MediumArrayBreadth-First SearchDepth-First Search77.8% acceptance6 companiesVideo
994.Rotting Oranges
MediumArrayBreadth-First SearchMatrix59.5% acceptance52 companiesVideo
1020.Number of Enclaves
MediumArrayBreadth-First SearchDepth-First Search72.2% acceptance5 companiesVideo
1034.Coloring A Border
MediumArrayBreadth-First SearchDepth-First Search51.8% acceptance3 companiesVideo
1072.Flip Columns For Maximum Number of Equal Rows
MediumArrayHash TableMatrix78.5% acceptance4 companiesVideo
1091.Shortest Path in Binary Matrix
MediumArrayBreadth-First SearchMatrix51.8% acceptance15 companiesVideo
Showing 1–50 of 157
How to use these solutions
Each solution breaks the problem into approaches, usually from brute force to the best one, and explains why each works. Code comes in Python, Java, C++ and other languages. Knowing why an approach works matters more in an interview than remembering the code.
- Try the problem first. Give it at least 20 minutes before you open the solution.
- Read every approach. The brute force shows you the problem; the faster ones show the pattern.
- Check the complexity. Note the time and space of each approach and what makes the difference.
- Write it yourself. Close the solution and code it from memory in the editor.
- Come back in a week. Solving it again later is what makes the pattern stick.