递归回溯没有返回值python

Question

完整问题在https://www.hackerrank.com/challenges/password-cracker/ 我想知道我的递归回溯实现有什么问题

问题：给定一个密码数组，如果 word 不是这些密码的组合，则返回“错误密码”

我想问一下如何从这里返回一个值；我可以打印解决方案，但不能以字符串形式返回。我不确定我能从这里做什么；我尝试在 word == '' 时返回一个值，但这没有用

def crackhelper(passwords,word,sol):
    #Check if theres some password that currently works
    print(sol)
    for password in passwords:
        if word[:len(password)]==password:
            sol+=password
            crackhelper(passwords,word[len(password):],sol)
            sol=sol[:-len(password)]

    return ''
def crack():
    word="wedowhatwemustbecausewecane"
    passwords="because can do must we what cane".split(' ')
    j=crackhelper(passwords,word,'')    
    print(j)
    #print(passwords)

Answer 1

def crack_helper(passwords, word, sol):
    # Check if there is some password that currently works.
    if word ==  "":
        return sol
    for password in passwords:
        if word[:len(password)] == password:
            sol += password
            s = crack_helper(passwords, word[len(password):], sol)
            if s != "No Result":
                sol = s
                return sol
            sol = sol[:-len(password)]
    return "No Result"

这应该可以完成这项工作:)