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

Statement

简体中文English

Metadata

• Link: 字符串中的第一个唯一字符
• Difficulty: Easy
• Tag: 队列 哈希表 字符串 计数

给定一个字符串 s ，找到 它的第一个不重复的字符，并返回它的索引 。如果不存在，则返回 -1 。

 

示例 1：

输入: s = "leetcode"
输出: 0

示例 2:

输入: s = "loveleetcode"
输出: 2

示例 3:

输入: s = "aabb"
输出: -1

 

提示:

• 1 <= s.length <= 105
• s 只包含小写字母

Metadata

• Link: First Unique Character in a String
• Difficulty: Easy
• Tag: Queue Hash Table String Counting

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.

Solution

Python 3

from collections import Counter


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

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最后更新: October 11, 2023