mirror of
https://github.com/TheAlgorithms/Java.git
synced 2025-07-08 02:04:31 +08:00
Enhance readability, add comments & function docs to SkylineProblem.java (#5534)
This commit is contained in:
@ -1,69 +1,68 @@
|
||||
package com.thealgorithms.others;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Iterator;
|
||||
import java.util.Scanner;
|
||||
|
||||
/**
|
||||
* The {@code SkylineProblem} class is used to solve the skyline problem using a
|
||||
* divide-and-conquer approach.
|
||||
* It reads input for building data, processes it to find the skyline, and
|
||||
* prints the skyline.
|
||||
*/
|
||||
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();
|
||||
}
|
||||
|
||||
/**
|
||||
* Adds a building with the given left, height, and right values to the
|
||||
* buildings list.
|
||||
*
|
||||
* @param left The left x-coordinate of the building.
|
||||
* @param height The height of the building.
|
||||
* @param right The right x-coordinate of the building.
|
||||
*/
|
||||
public void add(int left, int height, int right) {
|
||||
building[count++] = new Building(left, height, right);
|
||||
}
|
||||
|
||||
public void print(ArrayList<Skyline> skyline) {
|
||||
Iterator<Skyline> it = skyline.iterator();
|
||||
|
||||
while (it.hasNext()) {
|
||||
Skyline temp = it.next();
|
||||
System.out.print(temp.coordinates + "," + temp.height);
|
||||
if (it.hasNext()) {
|
||||
System.out.print(",");
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Computes the skyline for a range of buildings using the divide-and-conquer
|
||||
* strategy.
|
||||
*
|
||||
* @param start The starting index of the buildings to process.
|
||||
* @param end The ending index of the buildings to process.
|
||||
* @return A list of {@link Skyline} objects representing the computed skyline.
|
||||
*/
|
||||
public ArrayList<Skyline> findSkyline(int start, int end) {
|
||||
// Base case: only one building, return its skyline.
|
||||
if (start == end) {
|
||||
ArrayList<Skyline> list = new ArrayList<>();
|
||||
list.add(new Skyline(building[start].left, building[start].height));
|
||||
list.add(new Skyline(building[end].right, 0));
|
||||
|
||||
list.add(new Skyline(building[end].right, 0)); // Add the end of the building
|
||||
return list;
|
||||
}
|
||||
|
||||
int mid = (start + end) / 2;
|
||||
|
||||
ArrayList<Skyline> sky1 = this.findSkyline(start, mid);
|
||||
ArrayList<Skyline> sky2 = this.findSkyline(mid + 1, end);
|
||||
|
||||
return this.mergeSkyline(sky1, sky2);
|
||||
ArrayList<Skyline> sky1 = this.findSkyline(start, mid); // Find the skyline of the left half
|
||||
ArrayList<Skyline> sky2 = this.findSkyline(mid + 1, end); // Find the skyline of the right half
|
||||
return this.mergeSkyline(sky1, sky2); // Merge the two skylines
|
||||
}
|
||||
|
||||
/**
|
||||
* Merges two skylines (sky1 and sky2) into one combined skyline.
|
||||
*
|
||||
* @param sky1 The first skyline list.
|
||||
* @param sky2 The second skyline list.
|
||||
* @return A list of {@link Skyline} objects representing the merged skyline.
|
||||
*/
|
||||
public ArrayList<Skyline> mergeSkyline(ArrayList<Skyline> sky1, ArrayList<Skyline> sky2) {
|
||||
int currentH1 = 0;
|
||||
int currentH2 = 0;
|
||||
ArrayList<Skyline> skyline = new ArrayList<>();
|
||||
int maxH = 0;
|
||||
|
||||
// Merge the two skylines
|
||||
while (!sky1.isEmpty() && !sky2.isEmpty()) {
|
||||
if (sky1.get(0).coordinates < sky2.get(0).coordinates) {
|
||||
int currentX = sky1.get(0).coordinates;
|
||||
@ -96,6 +95,7 @@ public class SkylineProblem {
|
||||
}
|
||||
}
|
||||
|
||||
// Add any remaining points from sky1 or sky2
|
||||
while (!sky1.isEmpty()) {
|
||||
skyline.add(sky1.get(0));
|
||||
sky1.remove(0);
|
||||
@ -109,32 +109,45 @@ public class SkylineProblem {
|
||||
return skyline;
|
||||
}
|
||||
|
||||
/**
|
||||
* A class representing a point in the skyline with its x-coordinate and height.
|
||||
*/
|
||||
public class Skyline {
|
||||
|
||||
public int coordinates;
|
||||
public int height;
|
||||
|
||||
/**
|
||||
* Constructor for the {@code Skyline} class.
|
||||
*
|
||||
* @param coordinates The x-coordinate of the skyline point.
|
||||
* @param height The height of the skyline at the given coordinate.
|
||||
*/
|
||||
public Skyline(int coordinates, int height) {
|
||||
this.coordinates = coordinates;
|
||||
this.height = height;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* A class representing a building with its left, height, and right
|
||||
* x-coordinates.
|
||||
*/
|
||||
public class Building {
|
||||
|
||||
public int left;
|
||||
public int height;
|
||||
public int right;
|
||||
|
||||
/**
|
||||
* Constructor for the {@code Building} class.
|
||||
*
|
||||
* @param left The left x-coordinate of the building.
|
||||
* @param height The height of the building.
|
||||
* @param right The right x-coordinate of the building.
|
||||
*/
|
||||
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();
|
||||
}
|
||||
}
|
||||
|
Reference in New Issue
Block a user