59 lines
1.8 KiB
C#
59 lines
1.8 KiB
C#
using System;
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namespace DeukBot4.Utilities
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{
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public static class Lehvenstein
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{
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/// <summary>
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/// Calculates the Levenshtein distance between two strings--the number of changes that need to be made for the first string to become the second.
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/// </summary>
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/// <param name="first">The first string, used as a source.</param>
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/// <param name="second">The second string, used as a target.</param>
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/// <returns>The number of changes that need to be made to convert the first string to the second.</returns>
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/// <remarks>
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/// From http://www.merriampark.com/ldcsharp.htm
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/// </remarks>
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public static int LevenshteinDistance(string first, string second)
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{
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if (first == null)
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{
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throw new ArgumentNullException(nameof(first));
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}
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if (second == null)
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{
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throw new ArgumentNullException(nameof(second));
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}
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var n = first.Length;
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var m = second.Length;
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var d = new int[n + 1, m + 1]; // matrix
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if (n == 0) return m;
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if (m == 0) return n;
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for (var i = 0; i <= n; d[i, 0] = i++)
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{
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}
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for (var j = 0; j <= m; d[0, j] = j++)
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{
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}
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for (var i = 1; i <= n; i++)
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{
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for (var j = 1; j <= m; j++)
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{
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var cost = (second.Substring(j - 1, 1) == first.Substring(i - 1, 1) ? 0 : 1); // cost
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d[i, j] = Math.Min(
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Math.Min(
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d[i - 1, j] + 1,
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d[i, j - 1] + 1),
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d[i - 1, j - 1] + cost);
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}
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}
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return d[n, m];
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}
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}
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} |