29.Divide Two Integers
MediumBit ManipulationMath20.1% acceptance8 companiesVideo
Medium · With video · 125 results
78.Subsets
MediumArrayBacktrackingBit Manipulation82.7% acceptance21 companiesVideo
89.Gray Code
MediumBacktrackingBit ManipulationMath66.2% acceptance5 companiesVideo
90.Subsets II
MediumArrayBacktrackingBit Manipulation61.7% acceptance9 companiesVideo
137.Single Number II
MediumArrayBit Manipulation68.0% acceptance5 companiesVideo
187.Repeated DNA Sequences
MediumBit ManipulationHash FunctionHash Table54.3% acceptance7 companiesVideo
201.Bitwise AND of Numbers Range
MediumBit Manipulation49.4% acceptance5 companiesVideo
222.Count Complete Tree Nodes
MediumBinary SearchBinary TreeBit Manipulation72.6% acceptance7 companiesVideo
260.Single Number III
MediumArrayBit Manipulation70.2% acceptance7 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
351.Android Unlock Patterns
MediumBacktrackingBit ManipulationBitmask53.8% acceptance1 companyPremium elsewhere, free hereVideo
371.Sum of Two Integers
MediumBit ManipulationMath55.9% acceptance8 companiesVideo
393.UTF-8 Validation
MediumArrayBit Manipulation46.7% acceptance4 companiesVideo
397.Integer Replacement
MediumBit ManipulationDynamic ProgrammingGreedy37.9% acceptance4 companiesVideo
421.Maximum XOR of Two Numbers in an Array
MediumArrayBit ManipulationHash Table53.8% acceptance5 companiesVideo
464.Can I Win
MediumBit ManipulationBitmaskDynamic Programming31.7% acceptance4 companiesVideo
473.Matchsticks to Square
MediumArrayBacktrackingBit Manipulation42.3% acceptance9 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
672.Bulb Switcher II
MediumBit ManipulationBreadth-First SearchDepth-First Search51.2% acceptance1 companyVideo
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
779.K-th Symbol in Grammar
MediumBit ManipulationMathRecursion48.7% acceptance7 companiesVideo
784.Letter Case Permutation
MediumBacktrackingBit ManipulationString75.7% acceptance7 companiesVideo
861.Score After Flipping Matrix
MediumArrayBit ManipulationGreedy80.3% acceptance3 companiesVideo
898.Bitwise ORs of Subarrays
MediumArrayBit ManipulationDynamic Programming56.8% acceptance7 companiesVideo
957.Prison Cells After N Days
MediumArrayBit ManipulationHash Table39.0% acceptance1 companyVideo
1066.Campus Bikes II
MediumArrayBacktrackingBit Manipulation55.9% acceptance1 companyPremium elsewhere, free hereVideo
1177.Can Make Palindrome from Substring
MediumArrayBit ManipulationHash Table42.0% acceptance1 companyVideo
1238.Circular Permutation in Binary Representation
MediumBacktrackingBit ManipulationMath73.2% acceptance1 companyVideo
1239.Maximum Length of a Concatenated String with Unique Characters
MediumArrayBacktrackingBit Manipulation54.7% acceptance6 companiesVideo
1256.Encode Number
MediumBit ManipulationMathString70.0% acceptance1 companyPremium elsewhere, free hereVideo
1310.XOR Queries of a Subarray
MediumArrayBit ManipulationPrefix Sum78.1% acceptance3 companiesVideo
1318.Minimum Flips to Make a OR b Equal to c
MediumBit Manipulation71.9% acceptance2 companiesVideo
1371.Find the Longest Substring Containing Vowels in Even Counts
MediumBit ManipulationHash TablePrefix Sum75.7% acceptance6 companiesVideo
1386.Cinema Seat Allocation
MediumArrayBit ManipulationGreedy56.8% acceptance5 companiesVideo
1404.Number of Steps to Reduce a Number in Binary Representation to One
MediumBit ManipulationString63.8% acceptance7 companiesVideo
1442.Count Triplets That Can Form Two Arrays of Equal XOR
MediumArrayBit ManipulationHash Table84.9% acceptance2 companiesVideo
1457.Pseudo-Palindromic Paths in a Binary Tree
MediumBinary TreeBit ManipulationBreadth-First Search68.3% acceptance2 companiesVideo
1461.Check If a String Contains All Binary Codes of Size K
MediumBit ManipulationHash FunctionHash Table61.5% acceptance5 companiesVideo
1506.Find Root of N-Ary Tree
MediumBit ManipulationDepth-First SearchHash Table78.4% acceptance3 companiesPremium elsewhere, free hereVideo
1525.Number of Good Ways to Split a String
MediumBit ManipulationDynamic ProgrammingHash Table68.2% acceptance2 companiesVideo
1558.Minimum Numbers of Function Calls to Make Target Array
MediumArrayBit ManipulationGreedy62.9% acceptance1 companyVideo
1680.Concatenation of Consecutive Binary Numbers
MediumBit ManipulationMathSimulation66.6% acceptance3 companiesVideo
1734.Decode XORed Permutation
MediumArrayBit Manipulation67.0% acceptance1 companyVideo
1738.Find Kth Largest XOR Coordinate Value
MediumArrayBit ManipulationDivide and Conquer64.9% acceptance1 companyVideo
Showing 1–50 of 125
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.