387. First Unique Character in a String

Easy

10 Points

Hash Table

String

Queue

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 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