@Override
        public String toString() {
            return "CharCount [ch=" + ch + ", count=" + count + "]";
        }
http://www.geeksforgeeks.org/rearrange-a-string-so-that-all-same-characters-become-at-least-d-distance-away/
src/com/interview/string/RearrangeDuplicateCharsdDistanceAway.java