using System;

using System.Collections.Generic;

using System.Linq;

using FuzzyString;

public class Program

{

    public void Main()

    {

        string source = "Represent a number of objects with a written numeral 0-20 (with 0 representing a count of no objects).";

        string target = "Directly compare two objects with a measurable attribute in common, to see which object has \"more of\"/\"less of\" the attribute, and describe the difference.";

        Console.WriteLine(CompareStrings(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.HammingDistance(source, target));

        Console.WriteLine(FuzzyString.ComparisonMetrics.JaccardDistance(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.JaccardIndex(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.JaroDistance(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.JaroWinklerDistance(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.LongestCommonSubsequence(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.LongestCommonSubstring(source, target));

        //Console.WriteLine(FuzzyString.ComparisonMetrics.NormalizedLevenshteinDistance(source, target));

        Console.WriteLine(FuzzyString.ComparisonMetrics.OverlapCoefficient(source, target));

        Console.WriteLine(FuzzyString.ComparisonMetrics.RatcliffObershelpSimilarity(source, target));

        Console.WriteLine(FuzzyString.ComparisonMetrics.SorensenDiceIndex(source, target));

        Console.WriteLine(FuzzyString.ComparisonMetrics.TanimotoCoefficient(source, target));

    }

    public int ComputeLevenshteinDistance(string source, string target)

    {

        if ((source == null) || (target == null)) return 0;

        if ((source.Length == 0) || (target.Length == 0)) return 0;

        if (source == target) return source.Length;

        int sourceWordCount = source.Length;

        int targetWordCount = target.Length;

        // Step 1

        if (sourceWordCount == 0)

            return targetWordCount;

        if (targetWordCount == 0)

            return sourceWordCount;

        int[,] distance = new int[sourceWordCount + 1, targetWordCount + 1];

        // Step 2

        for (int i = 0; i <= sourceWordCount; distance[i, 0] = i++) ;

        for (int j = 0; j <= targetWordCount; distance[0, j] = j++) ;

        for (int i = 1; i <= sourceWordCount; i++)

        {

            for (int j = 1; j <= targetWordCount; j++)

            {

                // Step 3

                int cost = (target[j - 1] == source[i - 1]) ? 0 : 1;

                // Step 4

                distance[i, j] = Math.Min(Math.Min(distance[i - 1, j] + 1, distance[i, j - 1] + 1), distance[i - 1, j - 1] + cost);

            }

        }

        return distance[sourceWordCount, targetWordCount];

    }

    public double CompareStrings(string source, string target)

    {

        if (source == null && target == null) return 1;

        if (source == null   && target == null) return 1;

        if ((source == null) || (target == null)) return 0;

        if ((source.Length == 0) || (target.Length == 0)) return 0;

        if (source == target) return 1;

        int stepsToSame = ComputeLevenshteinDistance(source, target);

        double result = (1.0 - ((double)stepsToSame / (double)Math.Max(source.Length, target.Length)));

        // I removed the forced condition for now

        return result;

    }

​

}