我试图生成一个随机的字母序列，它应该等于一个特定的字符串。一个完全随机的迭代确实需要很长时间，所以我尝试了爬山的方法。它可以找到，直到目标和生成的句子的相似性几乎相同，但它从来没有达到100%。你知道这是什么问题吗？

import string
import random

sim = []
sen_list = []

def random_sen():
    goal = "The value of the intrinsic motivation cannot be underestimated"
    sen = []
    i = 0
    for i in range(len(goal)): 
        sen.append(random.choice(string.ascii_letters + ' '))
        i += 1

    sen = ''.join(sen)
    sen = sen.lower()
    return sen

def test_similarity(sen):
    i = 0
    # sen = random_sen()
    sen = updating_sen(sen)
    similarity_value = 0
    goal = "The value of the intrinsic motivation cannot be underestimated"

    for i in range(len(sen)):
        if goal[i] == sen[i]:
            similarity_value = similarity_value + 1

    similarity_value = similarity_value/len(sen)
    return similarity_value

def updating_sen(sen_max):
    goal = "The value of the intrinsic motivation cannot be underestimated"
    i = 0
    sen = []
    for i in range(len(goal)):
        if goal[i] == sen_max[i]:
            sen.append(goal[i])
        else:
            sen.append(random.choice(string.ascii_letters + ' '))
        i += 1

    sen = ''.join(sen)
    sen = sen.lower()
    return sen

def play():
    counter = 1 
    sen_max = random_sen()

    while(1):
        sen = updating_sen(sen_max)
        similarity_value = test_similarity(sen)
        sim.append(similarity_value)
        sen_list.append(sen)

        if similarity_value == 1:
            print("The monkey can call himself Shakespear now!! The sentence is %s" % (sen_max))
            break
        if similarity_value != 1:
            counter = counter + 1
        if counter % 10000 == 0:
            sim_max = max(sim)
            max_index = sim.index(sim_max)
            sen_max = sen_list[max_index]
            print ("Try number %d. This is the sim_max value: %s. The sentence is: %s" % (counter,sim_max, sen_max))
    return  sen_max

sen_max = play()