Ruudukko

import java.util.*;
import java.io.*;

public class ruudut2 {


	public static void main(String[] args) throws IOException {

		// Scanner input = new Scanner(System.in);
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String[] parts = br.readLine().split(" ");
		
		int n = Integer.parseInt(parts[0]);  // ruudukon koko
		int m = Integer.parseInt(parts[1]); // operaatioiden maara
		

		int[] y1 = new int[m];  // alkuarvot
		int[] y2 = new int[m]; 
		int[] x1 = new int[m]; 
		int[] x2 = new int[m]; 
		
		char[][] taulu = new char[n][n];

		for (int i = 0; i < n; i++) {
		  for (int i2 = 0; i2 < n; i2++) {
			taulu[i][i2] = '.';
		  }
		}
		
		for (int i = 0; i < m; i++) {
			String[] parts2 = br.readLine().split(" ");
			y1[i] = Integer.parseInt(parts2[0]);
			x1[i] = Integer.parseInt(parts2[1]);
			y2[i] = Integer.parseInt(parts2[2]);
			x2[i] = Integer.parseInt(parts2[3]);
		}
		
		// input.close(); 
		

		
		StringBuilder sb = new StringBuilder();
		
		
		int[][] flip = new int[n+1][n+1];
		
		int y11 = 0;
		int x11 = 0;
		int y22 = 0;
		int x22 = 0;		
		
		for (int i2 = 0; i2 < m; i2++) {
			
				y11 = y1[i2] - 1;
				x11 = x1[i2] - 1;
				y22 = y2[i2] - 1;
				x22 = x2[i2] - 1;
				
            flip[y11][x11] += 1;
            if (x22 + 1 < n) flip[y11][x22 + 1] -= 1;
            if (y22 + 1 < n) flip[y22 + 1][x11] -= 1;
            if (y22 + 1 < n && x22 + 1 < n) flip[y22 + 1][x22 + 1] += 1;			
	
		}
		
		// Prefix sum horizontally
	     for (int i = 0; i < n; i++) {
            for (int j = 1; j < n; j++) {
                flip[i][j] += flip[i][j - 1];
            }
        }	

		// Prefix sum vertically
        for (int j = 0; j < n; j++) {
            for (int i = 1; i < n; i++) {
                flip[i][j] += flip[i - 1][j];
            }
        }

		

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
				
				if (flip[i][j] % 2 == 1) {
					taulu[i][j] = (taulu[i][j] == '.') ? '#' : '.';
				}
				
                }
            }

		// tulostus
		
		// sb.append(x[t-1]).append('\n');
		
		
		// System.out.println(dy + " " + dx);	


        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
				
				sb.append(taulu[i][j]);
				
                }
				sb.append('\n');
            }



		System.out.print(sb.toString());
		
    }  // main
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 2, 3

Verdict: ACCEPTED

Test 4

Group: 3

Verdict: ACCEPTED

Test 5

Group: 3

Verdict: ACCEPTED