private void printLevel(Map<Integer,List<Node>> map){
        for(Integer key : map.keySet()){
            List<Node> listNodes = map.get(key);
            for(Node n : listNodes){
                System.out.print(n.data + " ");
            }
            System.out.println();
        }
    }
http://www.geeksforgeeks.org/print-binary-tree-vertical-order-set-2/
src/com/interview/tree/VerticalTreePrinting.java