import java.util.ArrayList; import java.util.Iterator; import java.util.Scanner; public class SkylineProblem { Building[] building; int count; public void run() { Scanner sc = new Scanner(System.in); int num = sc.nextInt(); this.building = new Building[num]; for(int i = 0; i < num; i++) { String input = sc.next(); String[] data = input.split(","); this.add(Integer.parseInt(data[0]), Integer.parseInt(data[1]), Integer.parseInt(data[2])); } this.print(this.findSkyline(0, num - 1)); sc.close(); } public void add(int left, int height, int right) { building[count++] = new Building(left, height, right); } public void print(ArrayList skyline) { Iterator it = skyline.iterator(); while(it.hasNext()) { Skyline temp = it.next(); System.out.print(temp.coordinates + "," + temp.height); if(it.hasNext()) { System.out.print(","); } } } public ArrayList findSkyline(int start, int end) { if(start == end) { ArrayList list = new ArrayList<>(); list.add(new Skyline(building[start].left, building[start].height)); list.add(new Skyline(building[end].right, 0)); return list; } int mid = (start + end) / 2; ArrayList sky1 = this.findSkyline(start, mid); ArrayList sky2 = this.findSkyline(mid + 1, end); return this.mergeSkyline(sky1, sky2); } public ArrayList mergeSkyline(ArrayList sky1, ArrayList sky2) { int currentH1 = 0, currentH2 = 0; ArrayList skyline = new ArrayList<>(); int maxH = 0; while(!sky1.isEmpty() && !sky2.isEmpty()) { if(sky1.get(0).coordinates < sky2.get(0).coordinates) { int currentX = sky1.get(0).coordinates; currentH1 = sky1.get(0).height; if(currentH1 < currentH2) { sky1.remove(0); if(maxH != currentH2) skyline.add(new Skyline(currentX, currentH2)); } else { maxH = currentH1; sky1.remove(0); skyline.add(new Skyline(currentX, currentH1)); } } else { int currentX = sky2.get(0).coordinates; currentH2 = sky2.get(0).height; if(currentH2 < currentH1) { sky2.remove(0); if(maxH != currentH1) skyline.add(new Skyline(currentX, currentH1)); } else { maxH = currentH2; sky2.remove(0); skyline.add(new Skyline(currentX, currentH2)); } } } while(!sky1.isEmpty()) { skyline.add(sky1.get(0)); sky1.remove(0); } while(!sky2.isEmpty()) { skyline.add(sky2.get(0)); sky2.remove(0); } return skyline; } public class Skyline { public int coordinates; public int height; public Skyline(int coordinates, int height) { this.coordinates = coordinates; this.height = height; } } public class Building { public int left; public int height; public int right; public Building(int left, int height, int right) { this.left = left; this.height = height; this.right = right; } } public static void main(String[] args) { SkylineProblem skylineProblem = new SkylineProblem(); skylineProblem.run(); } }