Method numTilePossibilities

LetterTilePossibilities.java:19–25

(String tiles)

        return;
    }
    public int numTilePossibilities(String tiles) {
        HashSet<String> set = new HashSet<String>();
        Boolean visited[] = new Boolean[tiles.length()];
        Arrays.fill(visited, Boolean.FALSE);
        backtrack(tiles,"",set, visited);
        return set.size();
    }
}