QOJ.ac

QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#236402#7730. Convex CheckerfstqwqWA 1ms3816kbC++141.3kb2023-11-03 22:15:462023-11-03 22:15:47

Judging History

你现在查看的是最新测评结果

  • [2024-07-04 19:27:17]
  • hack成功,自动添加数据
  • (/hack/727)
  • [2024-07-04 19:17:30]
  • hack成功,自动添加数据
  • (/hack/726)
  • [2023-11-03 22:15:47]
  • 评测
  • 测评结果:WA
  • 用时:1ms
  • 内存:3816kb
  • [2023-11-03 22:15:46]
  • 提交

answer

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef double LD;
typedef pair <int, int> pii;



const LD PI = acos(-1.0);
#define cp const point &
struct point {
	LL x, y;
	point () {}
	point (LL xx, LL yy) { x = xx, y = yy; }
	point operator + (cp a) const { return {x + a.x, y + a.y}; }
	point operator - (cp a) const { return {x - a.x, y - a.y}; }
	bool operator < (cp a) const {
		return make_pair(x, y) < make_pair(a.x, a.y);
	}
};

LL det (point a, point b) {
	return a.x * b.y - b.x * a.y;
}

void work () {
	int n;
	cin >> n;
	vector <point> a;
	for (int i = 0; i < n; i++) {
		int x, y;
		cin >> x >> y;
		a.push_back({x, y});
	}
	if (det(a[1] - a[0], a[2] - a[0]) < 0) reverse(a.begin(), a.end());
	bool flag = true;
	double ans = 0;
	for (int i = 0; i < n; i++) {
		auto u = a[(i + 2) % n] - a[(i + 1) % n];
		auto v = a[i] - a[(i + 1) % n];
		auto uu = atan2(u.y, u.x);
		auto vv = atan2(v.y, v.x);
		auto d = vv - uu;
		if (d < 0) d += 2 * PI;
		if (abs(d) <= 1e-12 && abs(PI - d) <= 1e-12) flag = false;
		ans += d;
	}
	puts (flag && abs(ans - (n - 2) * PI) < 0.1 ? "Yes" : "No");
}

int main() {
	ios::sync_with_stdio(false); cin.tie(0);
	int T = 1;
	for (int ca = 1; ca <= T; ca ++)
		work();
}



Details

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Test #1:

score: 100
Accepted
time: 1ms
memory: 3672kb

input:

3
0 0
1 0
0 1

output:

Yes

result:

ok answer is YES

Test #2:

score: 0
Accepted
time: 0ms
memory: 3516kb

input:

4
0 0
0 1
1 1
1 0

output:

Yes

result:

ok answer is YES

Test #3:

score: 0
Accepted
time: 0ms
memory: 3804kb

input:

4
0 0
0 3
1 2
1 1

output:

Yes

result:

ok answer is YES

Test #4:

score: 0
Accepted
time: 0ms
memory: 3516kb

input:

3
0 0
0 0
0 0

output:

No

result:

ok answer is NO

Test #5:

score: 0
Accepted
time: 0ms
memory: 3816kb

input:

5
1 0
4 1
0 1
2 0
3 2

output:

No

result:

ok answer is NO

Test #6:

score: -100
Wrong Answer
time: 0ms
memory: 3688kb

input:

5
0 0
1000000000 0
1000000000 500000000
1000000000 1000000000
0 1000000000

output:

Yes

result:

wrong answer expected NO, found YES