【每日一题0712】有效字符串

您将得到一个字符串和一个有效单词列表(所有字母都是小写)。请编写一个函数,判断字符串是否由列表中的一个或多个单词组成。

题目难度:中等
题目来源:codewars

def valid_word(word, li): 
    pass
    
assert valid_word('hogwarts', ['hog', 'warts']) is True
assert valid_word('hogwarts', ['warts', 'hog']) is True
assert valid_word('hogwarts', ['war','ts', 'hog']) is True
assert valid_word('hogwarts', ['h','o','g','w','a','r','t','s']) is True
assert valid_word('hogwarts', ['hog', 'wart']) is False
assert valid_word('hogwarts', ['hogw', 'warts']) is False
def valid_word(word, li):
    my_dict = {}    # 存储子串及子串出现的位置
    for item in li:
        try:
            my_dict[item] = word.index(item)
        except: # index函数找不到子串时会报异常
            return False
    # 按子符串出现的位置对字典进行排序
    sorted_list = sorted(my_dict.items(), key = lambda kv:(kv[1], kv[0]))
    print(sorted_list)
    now_idx = 0
    
    # 检查字符串拼接是否正确
    for i in range(len(sorted_list)-1):
        now_idx += len(sorted_list[i][0])
        if now_idx != sorted_list[i+1][1]:
            return False
    return now_idx+len(sorted_list[-1][0]) == len(word)

assert valid_word('hogwarts', ['hog', 'warts']) is True
assert valid_word('hogwarts', ['warts', 'hog']) is True
assert valid_word('hogwarts', ['war', 'ts', 'hog']) is True
assert valid_word('hogwarts', ['h', 'o', 'g', 'w', 'a', 'r', 't', 's']) is True
assert valid_word('hogwarts', ['hog', 'wart']) is False
assert valid_word('hogwarts', ['hogw', 'warts']) is False

会不会有下面这种断言
assert valid_word(‘hogwarts’, [‘hogw’,‘hog’,‘warts’]) is True

你这个用例不会,但如果是valid_word(‘hoghogwarts’, [‘hog’, ‘warts’, ‘hog’])这样子的就不行了

def valid_word(word, li): 
    for item in li:
        word = word.replace(item, '')
    return not word

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