Bored Uolevi

#include <iostream>
#include <algorithm>

const int N = 2000;
bool crossed[N][N];
int gcd(int a, int b) {
	if (a < b) return gcd(b, a);
	if (b == 0) return a;
	return gcd(b, a % b);
}

void trace(int x1, int y1, int x2, int y2) {
	// 1 0 3 3
	if (x1 <= x2) {
		int dx = x2-x1;
		int dy = y2-y1;
		for (int k = 0; k < x2-x1; ++k) {
			int y = y1 + (k * dy) / dx;
			bool not_eq_y = ((k * dy) % dx != 0);
			int next = y1 + ((k+1) * dy) / dx;
			bool not_eq_next = (((k+1) * dy) % dx != 0);
			if (y - next == 0) {
				if (not_eq_y || not_eq_next) {
					crossed[x1 + k][y] = true;
				}
			} else if (y > next) {
				if (not_eq_y) crossed[x1 + k][y] = true;
				for (int i = y-1; i >= next; --i) {
					crossed[x1 + k][i] = true;
				}
			} else {
				if (not_eq_next) crossed[x1 + k][next] = true;
				for (int i = next - 1; i >= y; --i) {
					crossed[x1 + k][i] = true;
				}
			}
		}
	} else {
		trace(x2, y2, x1, y1);
	}
}


int main() {
	int n;
	std::cin >> n;
	for (int i = 0; i < n; ++i) {
		int x1, y1, x2, y2;
		std::cin >> x1 >> y1 >> x2 >> y2;
		trace(x1, y1, x2, y2);
	}
	int count = 0;
	for (int y = 0; y < N; ++y) {
		for (int x = 0; x < N; ++x) {
			count += (crossed[x][y] ? 1 : 0);
		}
	}
	std::cout << count << '\n';
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED