Given a string, find the first non-repeating character in it and return it’s index. If it doesn’t exist, return -1.
Examples:
s = "leetcode"
return 0.
s = "loveleetcode",
return 2.
Note: You may assume the string contain only lowercase letters.
Solution:
这题的思路是利用python的先把输入的字符串转化成Counter对象，然后顺序遍历原来的字符串，取出其中的字符，在看看所取出来的字符对应在Counter对象中的值，如果是1，说明找到了该字符，直接返回对应的index。
from collections import Counter
class Solution:
def firstUniqChar(self, s: str) -> int:
cs = Counter(s)
for i,c in enumerate(s):
if cs[c]==1:
return i
return -1
