C++ :

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <stack>
#include <vector>
#include <cstring>
const double pi=acos(-1.0);
using namespace std;
int g[111][111];
int main()
{
    int T;scanf("%d",&T);
    double sq1=0.25*pi;
    double sq2=pi/6+sqrt(3)/4;
    while(T--)
    {
        memset(g,0,sizeof(g));
        int num;scanf("%d",&num);
        for(int i=1;i<=num;i++)
        {
            int x,y;scanf("%d%d",&x,&y);
            g[x][y]=1;
        }
        double ans=0;
        for(int i=0;i<=100;i++)
        {
            for(int j=0;j<=100;j++)
            {
                double tttt=ans;
                int ss=g[i][j]+g[i+1][j]+g[i][j+1]+g[i+1][j+1];
                if(ss==1)
                {
                    ans+=sq1;
                }
                else if(ss>2)
                {
                    ans+=1;
                }
                else if(ss==2&&((g[i][j]==1&&g[i+1][j+1]==1)||(g[i][j+1]==1&&g[i+1][j]==1)))
                {
                    ans+=1;
                }
                else if(ss==2)
                {
                    ans+=sq2;
                }
            }
        }
        printf("%.5f\n",ans);
    }
    return 0;
}