29.Divide Two Integers
MediumBit ManipulationMath20.1% acceptance8 companiesVideo
With video · 263 results
67.Add Binary
EasyBit ManipulationMathSimulation58.4% acceptance17 companiesVideo
78.Subsets
MediumArrayBacktrackingBit Manipulation82.7% acceptance21 companiesVideo
89.Gray Code
MediumBacktrackingBit ManipulationMath66.2% acceptance5 companiesVideo
90.Subsets II
MediumArrayBacktrackingBit Manipulation61.7% acceptance9 companiesVideo
136.Single Number
EasyArrayBit Manipulation78.1% acceptance15 companiesVideo
137.Single Number II
MediumArrayBit Manipulation68.0% acceptance5 companiesVideo
187.Repeated DNA Sequences
MediumBit ManipulationHash FunctionHash Table54.3% acceptance7 companiesVideo
190.Reverse Bits
EasyBit ManipulationDivide and Conquer69.2% acceptance9 companiesVideo
191.Number of 1 Bits
EasyBit ManipulationDivide and Conquer77.7% acceptance11 companiesVideo
201.Bitwise AND of Numbers Range
MediumBit Manipulation49.4% acceptance5 companiesVideo
222.Count Complete Tree Nodes
MediumBinary SearchBinary TreeBit Manipulation72.6% acceptance7 companiesVideo
231.Power of Two
EasyBit ManipulationMathRecursion50.5% acceptance11 companiesVideo
260.Single Number III
MediumArrayBit Manipulation70.2% acceptance7 companiesVideo
266.Palindrome Permutation
EasyBit ManipulationHash TableString68.6% acceptance5 companiesPremium elsewhere, free hereVideo
268.Missing Number
EasyArrayBinary SearchBit Manipulation72.4% acceptance19 companiesVideo
287.Find the Duplicate Number
MediumArrayBinary SearchBit Manipulation64.7% acceptance22 companiesVideo
318.Maximum Product of Word Lengths
MediumArrayBit ManipulationString61.7% acceptance2 companiesVideo
320.Generalized Abbreviation
MediumBacktrackingBit ManipulationString61.0% acceptance1 companyPremium elsewhere, free hereVideo
338.Counting Bits
EasyBit ManipulationDynamic Programming80.5% acceptance9 companiesVideo
342.Power of Four
EasyBit ManipulationMathRecursion52.5% acceptance8 companiesVideo
351.Android Unlock Patterns
MediumBacktrackingBit ManipulationBitmask53.8% acceptance1 companyPremium elsewhere, free hereVideo
371.Sum of Two Integers
MediumBit ManipulationMath55.9% acceptance8 companiesVideo
389.Find the Difference
EasyBit ManipulationHash TableSorting60.8% acceptance6 companiesVideo
393.UTF-8 Validation
MediumArrayBit Manipulation46.7% acceptance4 companiesVideo
397.Integer Replacement
MediumBit ManipulationDynamic ProgrammingGreedy37.9% acceptance4 companiesVideo
401.Binary Watch
EasyBacktrackingBit Manipulation65.9% acceptance5 companiesVideo
405.Convert a Number to Hexadecimal
EasyBit ManipulationMath54.8% acceptance6 companiesVideo
421.Maximum XOR of Two Numbers in an Array
MediumArrayBit ManipulationHash Table53.8% acceptance5 companiesVideo
461.Hamming Distance
EasyBit Manipulation76.7% acceptance4 companiesVideo
464.Can I Win
MediumBit ManipulationBitmaskDynamic Programming31.7% acceptance4 companiesVideo
465.Optimal Account Balancing
HardArrayBacktrackingBit Manipulation50.9% acceptance12 companiesPremium elsewhere, free hereVideo
473.Matchsticks to Square
MediumArrayBacktrackingBit Manipulation42.3% acceptance9 companiesVideo
476.Number Complement
EasyBit Manipulation70.3% acceptance5 companiesVideo
477.Total Hamming Distance
MediumArrayBit ManipulationMath55.3% acceptance3 companiesVideo
491.Non-decreasing Subsequences
MediumArrayBacktrackingBit Manipulation63.1% acceptance3 companiesVideo
526.Beautiful Arrangement
MediumArrayBacktrackingBit Manipulation64.9% acceptance6 companiesVideo
638.Shopping Offers
MediumArrayBacktrackingBit Manipulation52.9% acceptance6 companiesVideo
645.Set Mismatch
EasyArrayBit ManipulationHash Table43.4% acceptance7 companiesVideo
672.Bulb Switcher II
MediumBit ManipulationBreadth-First SearchDepth-First Search51.2% acceptance1 companyVideo
691.Stickers to Spell Word
HardArrayBacktrackingBit Manipulation51.3% acceptance4 companiesVideo
693.Binary Number with Alternating Bits
EasyBit Manipulation69.8% acceptance5 companiesVideo
698.Partition to K Equal Sum Subsets
MediumArrayBacktrackingBit Manipulation38.6% acceptance8 companiesVideo
756.Pyramid Transition Matrix
MediumBit ManipulationBreadth-First SearchDepth-First Search60.6% acceptance3 companiesVideo
762.Prime Number of Set Bits in Binary Representation
EasyBit ManipulationMath78.7% acceptance2 companiesVideo
779.K-th Symbol in Grammar
MediumBit ManipulationMathRecursion48.7% acceptance7 companiesVideo
782.Transform to Chessboard
HardArrayBit ManipulationMath51.9% acceptance2 companiesVideo
784.Letter Case Permutation
MediumBacktrackingBit ManipulationString75.7% acceptance7 companiesVideo
805.Split Array With Same Average
HardArrayBit ManipulationBitmask27.5% acceptance6 companiesVideo
810.Chalkboard XOR Game
HardArrayBit ManipulationBrainteaser67.3% acceptance3 companiesVideo
Showing 1–50 of 263
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.