The letter 'z' was not a possible letter in mutation

C#/GAHelloWorld/Chromosome.cs

@@ -83,7 +83,7 @@ public Chromosome Mutate()
             char[] mutatedGene = this.Gene.ToCharArray();
 
             int randomIndex = rand.Next(0, this.Gene.Length);
-            int mutateChange = rand.Next(32, 122);
+            int mutateChange = rand.Next(32, 123);
 
             mutatedGene[randomIndex] = (char)mutateChange;
 

clojure/src/net/auxesia/chromosome.clj

@@ -50,7 +50,7 @@
   [c]
   (let [old-gene (:gene c)
 	    idx (rand-int (count old-gene))
-	    new-gene (assoc old-gene idx (char (mod (+ (int (get old-gene idx)) (+ 32 (rand-int 90))) 122)))]
+	    new-gene (assoc old-gene idx (char (mod (+ (int (get old-gene idx)) (+ 32 (rand-int 90))) 123)))]
     (Chromosome. new-gene (fitness new-gene))))
 
 (defn generate
@@ -69,4 +69,4 @@
   (let [pivot (rand-int (count *target-gene*))
 	    child1 (into (subvec (:gene c1) 0 pivot) (subvec (:gene c2) pivot))
 	    child2 (into (subvec (:gene c2) 0 pivot) (subvec (:gene c1) pivot))]
-    (vector (generate child1) (generate child2))))
+    (vector (generate child1) (generate child2))))

java/src/main/java/net/auxesia/Chromosome.java

@@ -113,7 +113,7 @@ public Chromosome mutate() {
 		char[] arr  = gene.toCharArray();
 		int idx     = rand.nextInt(arr.length);
 		int delta   = (rand.nextInt() % 90) + 32;
-		arr[idx]    = (char) ((arr[idx] + delta) % 122);
+		arr[idx]    = (char) ((arr[idx] + delta) % 123);
 
 		return new Chromosome(String.valueOf(arr));
 	}

python/gahelloworld.py

@@ -71,7 +71,7 @@ def mutate(self):
         gene = list(self.gene)
         delta = randint(32, 121)
         idx = randint(0, len(gene) - 1)
-        gene[idx] = chr((ord(gene[idx]) + delta) % 122)
+        gene[idx] = chr((ord(gene[idx]) + delta) % 123)
 
         return Chromosome(''.join(gene))
 
@@ -179,4 +179,4 @@ def evolve(self):
 		if pop.population[0].fitness == 0: break
 		else:pop.evolve()
 	else:
-		print("Maximum generations reached without success.")
+		print("Maximum generations reached without success.")

ruby/lib/gahelloworld.rb

@@ -23,7 +23,7 @@
 module GAHelloWorld
   RAND_SEED=srand
   TARGET_GENE='Hello World!'
-  ALLOWED_LETTERS = (32..122).to_a.map{|i| i.chr}
+  ALLOWED_LETTERS = (32..123).to_a.map{|i| i.chr}
 
   class Chromosome
     attr_reader :gene_ary, :target_ary, :gene

scala/src/main/scala/net/auxesia/Chromosome.scala

@@ -104,7 +104,7 @@ object Chromosome {
    */
   def mutate(ch: Chromosome) = {
     var arr = ch.gene.toArray
-    arr(Random.nextInt(ch.gene.length)) = (Random.nextInt(90) + 32).toChar
+    arr(Random.nextInt(ch.gene.length)) = (Random.nextInt(91) + 32).toChar
     Chromosome(arr.mkString)
   }
-}
+}