[Java] 교점에 별 만들기 (2차원배열, 최대사각형, 좌표 배열 전환)

2023.08.09 - [Coding Test/programmers] - [프로그래머스] 교점에 별 만들기

[프로그래머스] 교점에 별 만들기

 

import java.util.*;

class Solution {
    
    public static class Point {
        public final long x,y;
        
        private Point(long x, long y) {
            this.x = x;
            this.y = y;
        }
    }
    
    // 교점구하기
    private Point intersection(long a1, long b1, long c1, long a2, long b2, long c2) {
        double x = (double) (b1*c2-c1*b2)/(a1*b2-b1*a2);
        double y = (double) (c1*a2-a1*c2)/(a1*b2-b1*a2);

        if (x%1!=0 || y%1!=0) return null;
        return new Point((long)x,(long)y);
    }
    
    // 최대좌표찾기
    private Point getMax(List<Point> points){
        long x = Long.MIN_VALUE;
        long y = Long.MIN_VALUE;
        
        for (Point p: points){
            if (p.x>x) x = p.x;
            if (p.y>y) y = p.y;
        }
        
        return new Point(x,y);
    }
    
   // 최소좌표찾기
    private Point getMin(List<Point> points){
        long x = Long.MAX_VALUE;
        long y = Long.MAX_VALUE;
        
        for (Point p: points){
            if (p.x<x) x = p.x;
            if (p.y<y) y = p.y;
        }
        
        return new Point(x,y);
    }
    
      
    
    public String[] solution(int[][] line) {
        
        List<Point> points = new ArrayList<>();
        
        for (int i=0; i<line.length; i++) {
            for (int j=0; j<line.length; j++) {
                Point temp = intersection(line[i][0], line[i][1], line[i][2],
                                  line[j][0], line[j][1], line[j][2]); // 교점 구하기
                
                if (temp!=null){
                    points.add(temp);
                }
            }
        }
    
    
        // 최대최소 좌표 구하기
        Point maxpoint = getMax(points);
        Point minpoint = getMin(points);
        
        // 가로세로 길이
        int w = (int)(maxpoint.x - minpoint.x +1);
        int h = (int)(maxpoint.y - minpoint.y +1);
        System.out.println(w+", "+h);
        
        char[][] arr = new char[h][w];
        for (char[] row: arr) {
            Arrays.fill(row, '.');
        }
        
        // 좌표 -> 2차원배열
        for (Point p: points) {
            int x = (int)(p.x - minpoint.x); // 최소좌표를 0점
            int y = (int)(maxpoint.y - p.y); // 최대좌표와 뒤집기 (y축반대)
            arr[y][x] = '*';
        }
        
        String[] answer = new String[arr.length];
        for (int i=0; i<answer.length; i++) {
            answer[i] = new String(arr[i]);
        }
        return answer;
    }
    
}