first-unique-character-in-a-string.py

# Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.
#
#  
# Example 1:
# Input: s = "leetcode"
# Output: 0
# Example 2:
# Input: s = "loveleetcode"
# Output: 2
# Example 3:
# Input: s = "aabb"
# Output: -1
#
#  
# Constraints:
#
#
# 	1 <= s.length <= 105
# 	s consists of only lowercase English letters.
#
#


class Solution:
    def firstUniqChar(self, s: str) -> int:
        d = {}
        for char in s:
            if char in d:
                d[char] += 1
            else:
                d[char] = 1
        for i in range(len(s)):
            if d[s[i]] == 1:
                return i
        return -1