Find Most Repeated Characters Performance Benchmark

Which is the fastest method to find the most repeated character? This project is a benchmark application that compares the performance of different methods for finding repeated characters in a text.

Test Scenario

The benchmark compares the performance of the following methods:

• GetMostRepeatedCharacterWithCount: Finds the most repeated character using a dictionary-based approach.
• GetMostRepeatedCharacterWithCount2: Finds the most repeated character using a dictionary-based approach.
• FindMostRepeatedCharacters: Finds the most repeated character using an array-based approach.
• FindMostRepeatedCharactersUnsafe: Finds the most repeated character using unsafe code to improve performance.
• FindMostRepeatedCharactersLinq: Finds the most repeated character using LINQ.

The goal is to determine which method performs better in terms of finding the most repeated character.

Methods

GetMostRepeatedCharacterWithCount

This method uses a dictionary to find the most frequently occurring character in a text. It excludes space characters and calculates the number of each character in the text. Finally, it sorts the dictionary by number and selects the character with the highest number. Does not support Unicode characters.

GetMostRepeatedCharacterWithCount2

This method iterates through each character in the input text and counts the occurrences of each character. It uses a dictionary to store the character counts and returns the character with the highest count. Does not support Unicode characters.

FindRepeatedCharacters

This method counts the occurrences of each character in the input text using an array. It supports ASCII characters and calculates the character counts based on the ASCII value of the character as the index of the array. Support Unicode characters.

FindRepeatedCharactersUnsafe

This method counts the occurrences of each character in the input text using an array and unsafe code. It improves performance by directly accessing the character pointer and incrementing the count in the array. Support Unicode characters.

FindRepeatedCharacterLinq

This method uses LINQ to group the characters in the input text and calculates the number of repetitions for each character. It returns a dictionary of repeated characters.Support Unicode characters.

Results

The benchmark results can be found in the BenchmarkDotNet table format in the Results.md file.

BenchmarkDotNet=v0.13.5, OS=Windows 11 (10.0.22621.1702/22H2/2022Update/SunValley2) 11th Gen Intel Core i7-1165G7 2.80GHz, 1 CPU, 8 logical and 4 physical cores .NET SDK=7.0.203 [Host] : .NET 7.0.5 (7.0.523.17405), X64 RyuJIT AVX2 DefaultJob : .NET 7.0.5 (7.0.523.17405), X64 RyuJIT AVX2

Method	N	Mean	Error	StdDev
GetMostRepeatedCharacterWithCount	10	288.51 ns	2.833 ns	2.650 ns
GetMostRepeatedCharacterWithCount2	10	169.34 ns	3.367 ns	4.258 ns
FindRepeatedCharacters	10	104.62 ns	0.626 ns	0.585 ns
FindRepeatedCharactersUnsafe	10	97.20 ns	1.083 ns	1.013 ns
FindRepeatedCharacterLinq	10	467.53 ns	6.250 ns	5.846 ns
GetMostRepeatedCharacterWithCount	100	2,082.16 ns	33.993 ns	31.797 ns
GetMostRepeatedCharacterWithCount2	100	1,105.78 ns	10.033 ns	9.385 ns
FindRepeatedCharacters	100	153.08 ns	3.097 ns	7.882 ns
FindRepeatedCharactersUnsafe	100	165.92 ns	1.414 ns	1.323 ns
FindRepeatedCharacterLinq	100	3,814.08 ns	73.797 ns	65.419 ns
GetMostRepeatedCharacterWithCount	1000	16,066.66 ns	306.461 ns	449.207 ns
GetMostRepeatedCharacterWithCount2	1000	8,440.00 ns	167.260 ns	156.455 ns
FindRepeatedCharacters	1000	771.47 ns	14.773 ns	18.143 ns
FindRepeatedCharactersUnsafe	1000	713.07 ns	13.859 ns	21.164 ns
FindRepeatedCharacterLinq	1000	18,543.42 ns	183.907 ns	172.026 ns
GetMostRepeatedCharacterWithCount	10000	147,590.99 ns	1,962.791 ns	1,739.963 ns
GetMostRepeatedCharacterWithCount2	10000	80,075.18 ns	1,588.425 ns	1,408.097 ns
FindRepeatedCharacters	10000	6,266.70 ns	53.613 ns	50.150 ns
FindRepeatedCharactersUnsafe	10000	5,565.20 ns	52.678 ns	46.698 ns
FindRepeatedCharacterLinq	10000	144,340.50 ns	2,139.167 ns	2,000.978 ns

How to Run?

To run the benchmark, follow these steps:

1. Clone the repository to your local machine.
2. Open the solution in Visual Studio, Rider or any compatible IDE.
3. Build the solution to restore the dependencies. (dotnet build)
4. Run the RepeatedCharactersPerformanceBenchmark project. (dotnet run --configuration Release)
5. The benchmark will execute and display the results in the console.

Contributing

To contribute, please create an issue or pull request on the GitHub repository.