leetcode/work/3/Easy/Hash Table/387.first-unique-character-in-a-string.py

"""
387. First Unique Character in a String
Difficulty: Easy
https://leetcode.com/problems/first-unique-character-in-a-string/

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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

Explanation:

The character 'l' at index 0 is the first character that does not
occur at any other index.

Example 2:

Input: s = "loveleetcode"

Output: 2

Example 3:

Input: s = "aabb"

Output: -1



Constraints:

        • 1 <= s.length <= 10^5

        • s consists of only lowercase English letters.
"""

from collections import Counter


class Solution:
    def firstUniqChar(self, s: str) -> int:
        map = Counter(s)
        for i, c in enumerate(s):
            if map[c] == 1:
                return i
        return -1