python - 给定一个小写字符串's'，返回字符串中仅出现一次的第一个字符的索引

Question

""" 如果每个字符出现多次，则返回 -1。示例输入：s: "Who wants hot watermelon?. 输出：8."""

def findLastIndex(str, x): 
    index = -1
    for i in range(0, len(str)): 
        if str[i] == x: 
            index = i 
    return index 

# String in which char is to be found 
str = "Who wants hot watermelon"

# char whose index is to be found 
x = 's'

index = findLastIndex(str, x) 

if index == -1: 
    print("Character not found") 
else: 
    print(index) 

Answer 1

尝试这个：

def func(s):
    for i in range(len(s)):
        if s.count(s[i]) == 1:
            return i
    return -1

Answer 2

我认为这是一种简单的方法：

def f(s):
    for i,c in enumerate(s):
        if s.count(c) == 1:
            return i
    return -1

assert f("who wants hot watermelon?") ==  8
assert f("aa") == -1