First Unique Character in a String.md

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.

My code:

class Solution(object):
    def firstUniqChar(self, s):
        """
        :type s: str
        :rtype: int
        """
        tmp_dict={}
        for item in s:
            if item not in tmp_dict:
                tmp_dict[item]=1
            else:
                tmp_dict[item]+=1
        for i in range(len(s)):
            if tmp_dict[s[i]]==1:
                return i
        return -1
        

Solution: https://leetcode.com/problems/first-unique-character-in-a-string/