杭电计算几何

#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
# define rep(i,be,en) for(int i=be;i<=en;i++)
# define pre(i,be,en) for(int i=be;i>=en;i--)
#define ll long long
#define endl "\n"
#define LOCAL
#define pb push_back
typedef pair<ll, ll> PII;
#define eb emplace_back
#define sp(i) setprecision(i)
const int N = 5e5 + 10, INF = 0x3f3f3f3f;
const int eps=1e-8;
int n;
bool check(vector<PII>v,vector<PII>p)
{
    for(int j=0;j<v.size();j++)
    {
        int x=v[j].x;
        int y=v[j].y;
        bool tt=1;
        for(int i=0;i<p.size();i++)
        {
        int x1=p[i].x;
        int y1=p[i].y;
        bool ok=false;
        if(x==x1) ok=true;
        if(y==y1) ok=true;
        if(abs(y-y1)==abs(x-x1)) ok=true;
        if(!ok)
        {
            tt=0;
            break;
        }
        }
        if(tt) return true;
    }
    return false;
} 
void solve()
{
    scanf("%d",&n);
    vector<PII>p(n);
    for(int i=0;i<n;i++)
    {
        scanf("%d%d",&p[i].x,&p[i].y);
    }
    if(n<=2)
    {
        cout<<"YES"<<endl;
        return;
    }
    vector<PII>v;
    bool ok=false;
    for(int i=1;i<n&&!ok;i++)
    {
         int x1=p[i].x;
         int x2=p[1].x;
         int y1=p[i].y;
        int y2=p[1].y;
        if(x1==x2||y1==y2||abs(y2-y1)==abs(x2-x1))  continue;
        ok=true;
        for(int k2=-1;k2<=1;k2++)
        {
                int b2=y2-k2*x2;
                v.push_back({x1,k2*x1+b2});
        }
        //为2垂直
        for(int k1=-1;k1<=1;k1++)
        {
            int b1=y1-k1*x1;
             v.push_back({x2,k1*x2+b1});
        }
         for(int k1=-1;k1<=1;k1++)
         {
            for(int k2=-1;k2<=1;k2++)
            {
                if(k1==k2) continue;
                int b1=y1-k1*x1;
                int b2=y2-k2*x2;
                v.push_back({(b2-b1)/(k1-k2),k1*(b2-b1)/(k1-k2)+b1});
            }
         }
         if(ok) break;
     }
    if(v.size()==0)
    {
        cout<<"YES"<<endl;
        return;
    }
    if(check(v,p))
    {
        cout<<"YES"<<endl;
    }else
    {
        cout<<"NO"<<endl;
    }
}
signed main() {
    //#ifdef LOCAL
    //freopen("data.in.txt","r",stdin);
    //freopen("data.out.txt","w",stdout);
    //#endif
    int __ = 1;
    cin>>__;
    while (__--)
        {
            solve();
        }
    return 0;
}