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Solutions, explained

Every approach from brute force to the best one, with code in Python, Java, C++ and more.

Array447 String249 Hash Table190 Math173 Database113 Sorting100 Simulation93 Counting70 Two Pointers70 Bit Manipulation54 Greedy51 Matrix41 All topics

Easy · 976 results

Bitwise OR of Even Numbers in an Array

3688.Bitwise OR of Even Numbers in an Array

EasyArrayBit ManipulationSimulation84.9% acceptance2 companiesVideo

Majority Frequency Characters

3692.Majority Frequency Characters

EasyCountingHash TableString66.3% acceptanceVideo

Maximum Distance Between Unequal Words in Array I

3696.Maximum Distance Between Unequal Words in Array I

EasyArrayString81.7% acceptance1 companyPremium elsewhere, free hereVideo

Compute Decimal Representation

3697.Compute Decimal Representation

EasyArrayMath64.7% acceptance1 companyVideo

Compute Alternating Sum

3701.Compute Alternating Sum

EasyArraySimulation89.8% acceptanceVideo

Equal Score Substrings

3707.Equal Score Substrings

EasyPrefix SumString56.7% acceptanceVideo

Sum of Elements With Frequency Divisible by K

3712.Sum of Elements With Frequency Divisible by K

EasyArrayCountingHash Table77.7% acceptanceVideo

Smallest Missing Multiple of K

3718.Smallest Missing Multiple of K

EasyArrayHash Table71.5% acceptanceVideo

Remove Zeros in Decimal Representation

3726.Remove Zeros in Decimal Representation

EasyMathSimulation75.7% acceptanceVideo

Find Missing Elements

3731.Find Missing Elements

EasyArrayHash TableSorting88.6% acceptance2 companiesVideo

Minimum Moves to Equal Array Elements III

3736.Minimum Moves to Equal Array Elements III

EasyArrayMath81.0% acceptance1 companyVideo

Minimum Distance Between Three Equal Elements I

3740.Minimum Distance Between Three Equal Elements I

EasyArrayHash Table73.4% acceptance2 companiesVideo

Maximize Expression of Three Elements

3745.Maximize Expression of Three Elements

EasyArrayEnumerationGreedy72.3% acceptanceVideo

Minimum Number of Flips to Reverse Binary String

3750.Minimum Number of Flips to Reverse Binary String

EasyBit ManipulationMathString75.5% acceptanceVideo

Concatenate Non-Zero Digits and Multiply by Sum I

3754.Concatenate Non-Zero Digits and Multiply by Sum I

EasyMath66.2% acceptance3 companiesVideo

Sort Integers by Binary Reflection

3769.Sort Integers by Binary Reflection

EasyArraySorting60.2% acceptanceVideo

Absolute Difference Between Maximum and Minimum K Elements

3774.Absolute Difference Between Maximum and Minimum K Elements

EasyArraySorting74.8% acceptanceVideo

Mirror Distance of an Integer

3783.Mirror Distance of an Integer

EasyMath91.5% acceptance2 companiesVideo

Find Users with High Token Usage

3793.Find Users with High Token Usage

Easy59.4% acceptanceVideo

Reverse String Prefix

3794.Reverse String Prefix

EasyStringTwo Pointers88.5% acceptance1 companyVideo

Largest Even Number

3798.Largest Even Number

EasyString68.5% acceptanceVideo

Count Residue Prefixes

3803.Count Residue Prefixes

EasyHash TableString65.2% acceptance2 companiesVideo

Vowel-Consonant Score

3813.Vowel-Consonant Score

EasySimulationString53.3% acceptanceVideo

Reverse Letters Then Special Characters in a String

3823.Reverse Letters Then Special Characters in a String

EasySimulationStringTwo Pointers81.5% acceptanceVideo

Count Monobit Integers

3827.Count Monobit Integers

EasyBit ManipulationEnumeration66.0% acceptance1 companyVideo

Count Dominant Indices

3833.Count Dominant Indices

EasyArrayEnumeration65.8% acceptanceVideo

Weighted Word Mapping

3838.Weighted Word Mapping

EasyArraySimulationString90.7% acceptance2 companiesVideo

Toggle Light Bulbs

3842.Toggle Light Bulbs

EasyArrayHash TableSimulation71.2% acceptance1 companyVideo

Smallest Pair With Different Frequencies

3852.Smallest Pair With Different Frequencies

EasyArrayCountingHash Table68.5% acceptance1 companyVideo

Trim Trailing Vowels

3856.Trim Trailing Vowels

EasyString77.2% acceptanceVideo

Minimum Capacity Box

3861.Minimum Capacity Box

EasyArray72.8% acceptanceVideo

First Unique Even Element

3866.First Unique Even Element

EasyArrayCountingHash Table65.6% acceptanceVideo

Count Commas in Range

3870.Count Commas in Range

EasyMath78.0% acceptanceVideo

Construct Uniform Parity Array I

3875.Construct Uniform Parity Array I

EasyArrayMath85.8% acceptance2 companiesVideo

Minimum Absolute Difference Between Two Values

3880.Minimum Absolute Difference Between Two Values

EasyArrayEnumeration66.2% acceptance1 companyVideo

First Matching Character From Both Ends

3884.First Matching Character From Both Ends

EasyStringTwo Pointers81.5% acceptanceVideo

Traffic Signal Color

3894.Traffic Signal Color

EasyMathSimulationString82.7% acceptance1 companyVideo

Find the Degree of Each Vertex

3898.Find the Degree of Each Vertex

EasyArrayGraphMatrix91.8% acceptanceVideo

Smallest Stable Index I

3903.Smallest Stable Index I

EasyArray76.5% acceptanceVideo

Valid Digit Number

3908.Valid Digit Number

EasyMath69.8% acceptanceVideo

Valid Elements in an Array

3912.Valid Elements in an Array

EasyArray56.7% acceptanceVideo

Count Indices With Opposite Parity

3917.Count Indices With Opposite Parity

EasyArray80.5% acceptanceVideo

Score Validator

3921.Score Validator

EasyArraySimulationString72.5% acceptanceVideo

Concatenate Array With Reverse

3925.Concatenate Array With Reverse

EasyArraySimulation91.1% acceptanceVideo

Check Adjacent Digit Differences

3931.Check Adjacent Digit Differences

EasyString77.1% acceptanceVideo

Minimum Swaps to Move Zeros to End

3936.Minimum Swaps to Move Zeros to End

EasyArrayTwo Pointers59.7% acceptanceVideo

Limit Occurrences in Sorted Array

3940.Limit Occurrences in Sorted Array

EasyArrayTwo Pointers72.6% acceptanceVideo

Digit Frequency Score

3945.Digit Frequency Score

EasyHash TableMath90.7% acceptanceVideo

Exactly One Consecutive Set Bits Pair

3950.Exactly One Consecutive Set Bits Pair

EasyBit Manipulation50.4% acceptanceVideo

Sum of Compatible Numbers in Range I

3954.Sum of Compatible Numbers in Range I

EasyBit ManipulationDynamic ProgrammingEnumeration58.4% acceptanceVideo

Showing 901–950 of 976

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.

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