public static void main(String args[]) {
        int [][] buildings = {{1,3,4},{3,4,4},{2,6,2},{8,11,4}, {7,9,3},{10,11,2}};
        SkylineDrawing sd = new SkylineDrawing();
        List<int[]> criticalPoints = sd.getSkyline(buildings);
        criticalPoints.forEach(cp -> System.out.println(cp[0] + " " + cp[1]));

    }
Represents either start or end of building
src/com/interview/geometry/SkylineDrawing.java