题解 | 找出字符串中第一个只出现一次的字符

def only_one_word(s):
        word_dict = {}
        for word in s:
            if word not in word_dict:
                word_dict[word] = 1
            else:
                word_dict[word] += 1

        for key, value in word_dict.items():
            if value == 1:
                return key
        return -1
s = input().strip()
print(only_one_word(s))