Initial data commit

Task/Evolutionary-algorithm/Common-Lisp/evolutionary-algorithm-2.lisp

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+(defun unfit (s1 s2)
+  (loop for a across s1
+	for b across s2 count(char/= a b)))
+
+(defun mutate (str alp n) ; n: number of chars to mutate
+  (let ((out (copy-seq str)))
+    (dotimes (i n) (setf (char out (random (length str)))
+			 (char alp (random (length alp)))))
+    out))
+
+(defun evolve (changes alpha target)
+  (loop for gen from 1
+	with f2 with s2
+	with str = (mutate target alpha 100)
+	with fit = (unfit target str)
+	while (plusp fit) do
+	(setf s2 (mutate str alpha changes)
+	      f2 (unfit target s2))
+	(when (> fit f2)
+	  (setf str s2 fit f2)
+	  (format t "~5d: ~a (~d)~%" gen str fit))))
+
+(evolve 1 " ABCDEFGHIJKLMNOPQRSTUVWXYZ" "METHINKS IT IS LIKE A WEASEL")