DouKaku?

import random

GOAL = "METHINKSITISAWEASEL"

DOMAIN = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

SET_SIZE = 300
MULTIPLY = 5

def create_random():
    s = ""
    for i in range(len(GOAL)):
        s += random.choice(DOMAIN)
    return s

def initial_set():
    s = []
    for i in range(SET_SIZE):
        s += [create_random()]
    return s

def mutate(s):
    i = random.randrange(0, len(s))
    result = s[:i] + random.choice(DOMAIN) + s[i+1:]
    return result

def mutate_set(s):
    result = []
    for e in s:
        for i in range(MULTIPLY):
            result.append(mutate(e))
    return result

def distance(s):
    d = 0
    for c1, c2 in zip(s, GOAL):
        if c1 != c2:
            d += 1
    return d

def sorted_set(s):
    work = [(distance(e), e) for e in s]

    def mycmp(e1, e2):
        return cmp(e1[0], e2[0])
    work.sort(mycmp)
    return work

def main():
    s = initial_set()
    i = 0

    while True:
        new_s = mutate_set(s)
        s = [e for (d,e) in sorted_set(new_s)[:SET_SIZE]]
        print "%04d: %2d %s"%(i + 1, distance(s[0]), s[0])
        if s[0] == GOAL:
            break
        i += 1

if __name__=='__main__':
    main()