Ruudukko

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

n, m = map(int, input().split())
ruudukko = [bytearray(n+2) for i in range(n+2)]
for i in range(m):
    y1, x1, y2, x2 = map(int, input().split())
    ruudukko[y1][x1] ^= 1
    ruudukko[y1][x2 + 1] ^= 1
    ruudukko[y2 + 1][x1] ^= 1
    ruudukko[y2 + 1][x2 + 1] ^= 1

s = bytearray(n)
rivi = 0
for i in range(1, n+1):
    x = 0
    for j in range(1, n+1):
        ruudukko[i+1][j] ^= ruudukko[i][j]
        x ^= ruudukko[i][j]
        ruudukko[i][j] = b".#"[x]
    ruudukko[i] = ruudukko[i][1:n+1].decode()

print("\n".join(ruudukko[1:n+1]))

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