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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#343591 | #7730. Convex Checker | 5ab | WA | 17ms | 6780kb | C++20 | 2.0kb | 2024-03-02 19:58:21 | 2024-03-02 19:58:21 |
Judging History
answer
/* name: 7730
* author: 5ab
* created at: 2024-03-02
*/
#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define ssz(x) (int((x).size()))
auto chmax = [](auto& x, auto y) { if (x < y) x = y; };
auto chmin = [](auto& x, auto y) { if (y < x) x = y; };
using ll = long long;
const int N = 2e5;
struct point
{
int x, y;
point operator-(const point& q) const {
return { x - q.x, y - q.y };
}
bool operator==(const point& q) const {
return x == q.x && y == q.y;
}
}
a[N], b[N];
inline ll cross(const point& p, const point& q) {
return 1ll * p.x * q.y - 1ll * q.x * p.y;
}
inline ll dot(const point& p, const point& q) {
return 1ll * p.x * q.x + 1ll * p.y * q.y;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
for (int i = 0; i < n; i++)
cin >> a[i].x >> a[i].y;
copy(a, a + n, b);
swap(b[0], *min_element(b, b + n, [](auto& p, auto& q) {
return p.x == q.x ? p.y < q.y : p.x < q.x;
}));
sort(b + 1, b + n, [&](auto& p, auto& q) {
ll t = cross(p - a[0], q - a[0]);
return t ? t > 0 : dot(q - p, p - a[0]) > 0;
});
int lm = unique(b, b + n) - b;
vector<point> cv;
for (int i = 0; i < lm; i++)
{
while (ssz(cv) > 1 && cross(b[i] - cv.back(), cv.back() - end(cv)[-2]) >= 0)
cv.pop_back();
// cerr << b[i].x << " " << b[i].y << endl;
cv.push_back(b[i]);
}
// cerr << ssz(cv) << " " << lm << endl;
if (ssz(cv) != n)
{
cout << "No\n";
return 0;
}
auto check = [&]() -> bool
{
int sp = find(a, a + n, cv[0]) - a;
// cerr << sp << endl;
if (sp == n)
return 0;
for (int i = 0, j = sp; i < n; i++, j = (j + 1) % n)
if (a[j] != cv[i])
{
// cerr << i << " " << j << " " << cv[i].x << " " << cv[i].y << endl;
return 0;
}
return 1;
};
bool res = check();
reverse(all(cv));
cout << ((check() || res) ? "Yes" : "No") << "\n";
return 0;
}
// started coding at: 03-02 19:14:06
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 0ms
memory: 5892kb
input:
3 0 0 1 0 0 1
output:
Yes
result:
ok answer is YES
Test #2:
score: 0
Accepted
time: 0ms
memory: 3612kb
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: 3600kb
input:
4 0 0 0 3 1 2 1 1
output:
Yes
result:
ok answer is YES
Test #4:
score: 0
Accepted
time: 1ms
memory: 3832kb
input:
3 0 0 0 0 0 0
output:
No
result:
ok answer is NO
Test #5:
score: 0
Accepted
time: 0ms
memory: 3612kb
input:
5 1 0 4 1 0 1 2 0 3 2
output:
No
result:
ok answer is NO
Test #6:
score: 0
Accepted
time: 0ms
memory: 3576kb
input:
5 0 0 1000000000 0 1000000000 500000000 1000000000 1000000000 0 1000000000
output:
No
result:
ok answer is NO
Test #7:
score: 0
Accepted
time: 1ms
memory: 5840kb
input:
5 0 0 1000000000 0 1000000000 499999999 1000000000 1000000000 0 1000000000
output:
No
result:
ok answer is NO
Test #8:
score: 0
Accepted
time: 0ms
memory: 3828kb
input:
5 0 0 999999999 0 1000000000 50000000 999999999 1000000000 0 1000000000
output:
Yes
result:
ok answer is YES
Test #9:
score: -100
Wrong Answer
time: 17ms
memory: 6780kb
input:
128312 5578014 410408218 5585076 410404717 5588011 410403262 5588473 410403033 5589740 410402405 5593295 410400643 5593751 410400417 5597248 410398684 5598935 410397848 5600618 410397014 5605185 410394751 5610514 410392111 5614281 410390245 5617263 410388768 5621142 410386847 5630840 410382045 56310...
output:
No
result:
wrong answer expected YES, found NO