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http://rosettacode.org/wiki/Evolutionary_algorithm
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■ Evolutionary
  § static
    target⦂ String: "METHINKS IT IS LIKE A WEASEL"
    letter⦂ char[]: "ABCDEFGHIJKLMNOPQRSTUVWXYZ ".toCharArray°
    parent⦂ String
    random⦂ java.util.Random°
    rate⦂ double: 0.5
    C⦂ int: 1000

    ▶ fittness⦂ int    · computes the 'closeness' of its
    • argument⦂ String · to the target string
      closeness⦂ int: 0
      ∀ i ∈ 0 … target.length°
        closeness◥ if target.charAt i = argument.charAt i
      return closeness

    ▶ mutate⦂ String · returns a copy of the
    • given⦂ String  · with some characters probably mutated
    • rate⦂ double
      copy⦂ char[]: given.toCharArray°
      ∀ i ∈ 0 … given.length°
        copy[i]: letter[random.nextInt letter.length] if rate > random.nextDouble°
      return String.valueOf copy

    ▶ main
    • args⦂ String[]
      ancest⦂ StringBuilder°
      ∀ i ∈ 0 … target.length°
        ancest.append letter[random.nextInt letter.length]
      parent: ancest.toString°
      currentFittness⦂ int: fittness parent
      generation⦂ int: 0
      🔁 until the parent ≈ target
        if fittness parent > currentFittness
           currentFittness: fittness parent
           System.out.println "Fittness of generation #⸨generation⸩ is ⸨currentFittness⸩"
        for each time from 1 to C
            mutation⦂ String: mutate parent, rate
            parent: mutation if fittness parent < fittness mutation
        generation◥
      System.out.println "Target reached by generation #⸨generation⸩"