Initial data commit

Task/Evolutionary-algorithm/Nim/evolutionary-algorithm.nim

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+import random
+
+const
+  Target = "METHINKS IT IS LIKE A WEASEL"
+  Alphabet = " ABCDEFGHIJLKLMNOPQRSTUVWXYZ"
+  P = 0.05
+  C = 100
+
+proc negFitness(trial: string): int =
+  for i in 0 .. trial.high:
+    if Target[i] != trial[i]:
+      inc result
+
+proc mutate(parent: string): string =
+  for c in parent:
+    result.add (if rand(1.0) < P: sample(Alphabet) else: c)
+
+randomize()
+
+var parent = ""
+for _ in 1..Target.len:
+  parent.add sample(Alphabet)
+
+var i = 0
+while parent != Target:
+  var copies = newSeq[string](C)
+  for i in 0 .. copies.high:
+    copies[i] = parent.mutate()
+
+  var best = copies[0]
+  for i in 1 .. copies.high:
+    if negFitness(copies[i]) < negFitness(best):
+      best = copies[i]
+  parent = best
+
+  echo i, " ", parent
+  inc i