Initial data commit

Task/Evolutionary-algorithm/C-sharp/evolutionary-algorithm.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+static class Program {
+    static Random Rng = new Random((int)DateTime.Now.Ticks);
+
+    static char NextCharacter(this Random self) {
+        const string AllowedChars = " ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        return AllowedChars[self.Next() % AllowedChars.Length];
+    }
+
+    static string NextString(this Random self, int length) {
+        return String.Join("", Enumerable.Repeat(' ', length)
+            .Select(c => Rng.NextCharacter()));
+    }
+
+    static int Fitness(string target, string current) {
+        return target.Zip(current, (a, b) => a == b ? 1 : 0).Sum();
+    }
+
+    static string Mutate(string current, double rate) {
+        return String.Join("", from c in current
+               select Rng.NextDouble() <= rate ? Rng.NextCharacter() : c);
+    }
+
+    static void Main(string[] args) {
+        const string target = "METHINKS IT IS LIKE A WEASEL";
+        const int C = 100;
+        const double P = 0.05;
+
+        // Start with a random string the same length as the target.
+        string parent = Rng.NextString(target.Length);
+
+        Console.WriteLine("START:       {0,20} fitness: {1}",
+            parent, Fitness(target, parent));
+        int i = 0;
+
+        while (parent != target) {
+            // Create C mutated strings + the current parent.
+            var candidates = Enumerable.Range(0, C + 1)
+                .Select(n => n > 0 ? Mutate(parent, P) : parent);
+
+            // select the fittest
+            parent = candidates.OrderByDescending(c => Fitness(target, c)).First();
+
+            ++i;
+            Console.WriteLine("     #{0,6} {1,20} fitness: {2}",
+                i, parent, Fitness(target, parent));
+        }
+
+        Console.WriteLine("END: #{0,6} {1,20}", i, parent);
+    }
+}