Leetcode - First Unique Character in a String Solution — The Poor Coder

Given a string s, return the first non-repeating character in it and return its index. If it does not exist, return -1.

Example 1:

Text

Input: s = "leetcode"
Output: 0

Example 2:

Text

Input: s = "loveleetcode"
Output: 2

Example 3:

Text

Input: s = "aabb"
Output: -1

Constraints:

1 <= s.length <= 10⁵
s consists of only lowercase English letters.

Solution in Python#

Python

from collections import Counter
class Solution:
    def firstUniqChar(self, s: str) -> int:
        count = Counter(s)
        unique_chars = {x for x,y in count.items() if y==1}
        for i in range(len(s)):
            if s[i] in unique_chars:
                return i
        else:
            return -1

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Solution in Python#

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