Data update

Task/Levenshtein-distance-Alignment/C-sharp/levenshtein-distance-alignment.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Text;
+
+public class LevenshteinAlignment
+{
+    public static string[] Alignment(string a, string b)
+    {
+        a = a.ToLower();
+        b = b.ToLower();
+
+        int[,] costs = new int[a.Length + 1, b.Length + 1];
+
+        for (int j = 0; j <= b.Length; j++)
+            costs[0, j] = j;
+
+        for (int i = 1; i <= a.Length; i++)
+        {
+            costs[i, 0] = i;
+            for (int j = 1; j <= b.Length; j++)
+            {
+                costs[i, j] = Math.Min(1 + Math.Min(costs[i - 1, j], costs[i, j - 1]),
+                    a[i - 1] == b[j - 1] ? costs[i - 1, j - 1] : costs[i - 1, j - 1] + 1);
+            }
+        }
+
+        StringBuilder aPathRev = new StringBuilder();
+        StringBuilder bPathRev = new StringBuilder();
+
+        for (int i = a.Length, j = b.Length; i != 0 && j != 0;)
+        {
+            if (costs[i, j] == (a[i - 1] == b[j - 1] ? costs[i - 1, j - 1] : costs[i - 1, j - 1] + 1))
+            {
+                aPathRev.Append(a[--i]);
+                bPathRev.Append(b[--j]);
+            }
+            else if (costs[i, j] == 1 + costs[i - 1, j])
+            {
+                aPathRev.Append(a[--i]);
+                bPathRev.Append('-');
+            }
+            else if (costs[i, j] == 1 + costs[i, j - 1])
+            {
+                aPathRev.Append('-');
+                bPathRev.Append(b[--j]);
+            }
+        }
+
+        return new string[] { Reverse(aPathRev.ToString()), Reverse(bPathRev.ToString()) };
+    }
+
+    private static string Reverse(string s)
+    {
+        char[] charArray = s.ToCharArray();
+        Array.Reverse(charArray);
+        return new string(charArray);
+    }
+
+    public static void Main(string[] args)
+    {
+        string[] result = Alignment("rosettacode", "raisethysword");
+        Console.WriteLine(result[0]);
+        Console.WriteLine(result[1]);
+    }
+}