#include<iostream>
#include<cstdio>
#include<string>
#include<map>
#include<sstream>
#include<algorithm>
#include<vector>
#include<queue>
#include<set>
#include<cstring>
#include<stack>
#include<iomanip>
#include<math.h>
using namespace std;
int main()
{
int T;
while(scanf("%d",&T)!=EOF)
{
while(T)
{
int n;
scanf("%d",&n);
int i,j;
int sum=0;
set<pair<int,int> > v;
for(i=0;i<n;i++)
{
pair<int,int> p;
scanf("%d %d",&p.first,&p.second);
sum+=p.first;
p.first*=n;
v.insert(p);
}
bool find_set=true;
for(set<pair<int,int> >::iterator it=v.begin();it!=v.end();it++)
{
pair<int,int> temp1=*it;
pair<int,int> temp2;
temp2.first=2*sum-temp1.first;
temp2.second=temp1.second;
if(v.find(temp2)==v.end())
{
find_set=false;
break;
}
}
if(find_set)
cout<<"YES"<<endl;
else
cout<<"NO"<<endl;
T--;
}
}
return 0;
}
UVa 1595 Symmetry
最新推荐文章于 2024-04-09 19:27:05 发布