private RearrangeDuplicateCharsdDistanceAway getOuterType() {
            return RearrangeDuplicateCharsdDistanceAway.this;
        }
http://www.geeksforgeeks.org/rearrange-a-string-so-that-all-same-characters-become-at-least-d-distance-away/
src/com/interview/string/RearrangeDuplicateCharsdDistanceAway.java