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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#238941 | #7730. Convex Checker | yuxx | WA | 1ms | 7912kb | C++14 | 2.7kb | 2023-11-04 17:57:06 | 2023-11-04 17:57:06 |
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)
- [2023-12-08 14:40:48]
- hack成功,自动添加数据
- (//qoj.ac/hack/493)
- [2023-11-07 10:32:52]
- hack成功,自动添加数据
- (//qoj.ac/hack/426)
- [2023-11-07 10:28:41]
- hack成功,自动添加数据
- (//qoj.ac/hack/425)
- [2023-11-04 17:57:06]
- 提交
answer
#include <bits/stdc++.h>
using namespace std;
const int N=1e5+5;
const double eps=1e-7;
int n;
struct point {
double x, y;
point () {}
point (double a, double b) : x (a), y (b) {}
bool operator<(const point &a)const{
if(a.x==x)
{
return a.y>y;
}
return a.x>x;
}
point operator - (const point &b) {
return point (x - b.x, y - b.y);
}
};
point p[N], sp[N];
point er[N];
int cmp (double x) {
if (fabs (x) < eps) return 0;
return x > 0 ? 1 : -1;
}
double dis (point a, point b) {
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
double cp (point a, point b) {
return a.x * b.y - a.y * b.x;
}
int Andrew () {
sort(p+1,p+n+1);
int len=0;
for (int i=1;i<=n;i++){
while(len>1&&cmp(cp(sp[len]-sp[len-1],p[i]-sp[len-1]))<0)
{
len--;
}
sp[++len]=p[i];
}
int k=len;
for(int i=n-1;i>=1;i--)
{
while(len>k&&cmp(cp(sp[len]-sp[len-1],p[i]-sp[len-1]))<0)
{
len--;
}
sp[++len]=p[i];
}
return len;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>p[i].x>>p[i].y;
er[i]=p[i];
}
int t=Andrew();
reverse(er+1,er+n+1);
for(int i=1;i<t;i++)
{
sp[i+t-1]=sp[i];
}
if(n!=t-1)
{
// flag=1;
cout<<"NO";
return 0;
}
// for(int i=1;i<=n;i++)
// {
// cout<<er[i].x<<" "<<er[i].y<<endl;
// }
int flag1=0;
int flag2=0;
for(int i=1;i<=n+1;i++)
{
if(er[1].x==sp[i].x and er[1].y==sp[i].y)
{
for(int j=1;j<=n;j++)
{
//// cout<<er[j].x<<" "<<er[j].y<<" "<<sp[i+j-1].x<<" "<<sp[i+j-1].y<<endl;
if(er[j].x!=sp[i+j-1].x or er[j].y!=sp[i+j-1].y)
{
flag1=1;
// cout<<j<<" "<<i;
break;
}
}
break;
}
}
reverse(er+1,er+n+1);
for(int i=1;i<=n+1;i++)
{
if(er[1].x==sp[i].x and er[1].y==sp[i].y)
{
for(int j=1;j<=n;j++)
{
if(er[j].x!=sp[i+j-1].x or er[j].y!=sp[i+j-1].y)
{
flag2=1;
//cout<<j<<" "<<i;
break;
}
}
break;
}
}
if(flag1 and flag2)
{
cout<<"No";
}
else
{
cout<<"Yes";
}
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 1ms
memory: 7912kb
input:
3 0 0 1 0 0 1
output:
Yes
result:
ok answer is YES
Test #2:
score: 0
Accepted
time: 1ms
memory: 5732kb
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: 7844kb
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: 5736kb
input:
3 0 0 0 0 0 0
output:
NO
result:
ok answer is NO
Test #5:
score: 0
Accepted
time: 1ms
memory: 5868kb
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: 5800kb
input:
5 0 0 1000000000 0 1000000000 500000000 1000000000 1000000000 0 1000000000
output:
Yes
result:
wrong answer expected NO, found YES