first-unique-character-in-a-string

First Unique Character in a String

LeetCode #: 387

Difficulty: Easy

Topics: Hash Table, String.

Problems

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode",
return 2.
Note: You may assume the string contain only lowercase letters.