First Unique Character in a String

Description

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.

code

class Solution {
    public int firstUniqChar(String s) {
        for (int i = 0; i < s.length(); i++) {
            if (s.substring(i + 1).indexOf(s.charAt(i)) == -1 && 
                    s.substring(0, i).indexOf(s.charAt(i)) == -1) {
                return i;
            }
        }
        return -1;
    }
}