//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.

class FirstUniqueCharacterInAString {
    public int firstUniqChar(String s) {
        HashMap<Character, Integer> characters = new HashMap<Character, Integer>();
        for(int i = 0; i < s.length(); i++) {
            char current = s.charAt(i);
            if(characters.containsKey(current)) {
                characters.put(current, -1);
            } else {
                characters.put(current, i);
            }
        }
        
        int min = Integer.MAX_VALUE;
        for(char c: characters.keySet()) {
            if(characters.get(c) > -1 && characters.get(c) < min) {
                min = characters.get(c);
            }
        }
        
        return min == Integer.MAX_VALUE ? -1 : min;
        
    }
}