Language: C++

#include<cmath>
#include<algorithm>
#include<iostream>
#include<vector>
#include<climits>
#include<cfloat>

using namespace std;

double EPS = 1e-10;
const double PI = acos(-1);

double add(double a, double b){
  if(abs(a+b) < EPS * (abs(a)+abs(b)))return 0;
  return a+b;
}

struct point{
  double x, y;
  point(){}
  point(double x,double y) : x(x) , y(y){}
  
  point operator + (point p){
    return point(add(x,p.x), add(y,p.y));
  }
  
  point operator - (point p){
    return point(add(x,-p.x), add(y,-p.y));
  }
  
  point operator * (double d){
    return point(x*d,y*d);
  }
  
  point operator / (double d){
    return point(x/d,y/d);
  }
  
  bool operator == ( const point &p ) const {
    return abs(x-p.x) < EPS && abs(y-p.y) < EPS;
  }
};

double dot(point a, point b) {
  return (a.x * b.x + a.y * b.y);
}

double cross(point a, point b) {
  return (a.x * b.y - a.y * b.x);
}

int is_point_on_line(point a, point b, point c) {
  return cross(a-c, b-c)==0 && dot(a-c, b-c)<=0;
}

int is_intersected_ls(point a1, point a2, point b1, point b2) {
  
  if(cross(a1-a2,b1-b2)==0){
    return is_point_on_line(a1,a2,b1) || is_point_on_line(a1,a2,b2) 
      || is_point_on_line(b1,b2,a1) || is_point_on_line(b1,b2,a2);
  }
  else {
    return ( cross(a2-a1, b1-a1) * cross(a2-a1, b2-a1) < EPS ) &&
      ( cross(b2-b1, a1-b1) * cross(b2-b1, a2-b1) < EPS );
  }
}

int inside(point p, vector<point> ps){
  point a,b;
  a=b=p;
  b.x=DBL_MAX;
  n=ps.size();
  ps.push_back(ps[0]);
  double ymx=-DBL_MAX,ymn=DBL_MAX;
  for(int i=0;i<n;i++){
    ymx=max(ymx,ps[i].y);
    ymn=min(ymn,ps[i].y);
  }
  if(a.y<=ymn||a.y>=ymx)return 0;
  
  for(int i=0;i<n;i++){
    if(is_point_on_line(ps[i],ps[i+1],p))return 1;
  }
  
  int cnt1=0;
  for(int i=0;i<n;i++)
    if(is_point_on_line(a,b,ps[i]))cnt1++;
  
  int cnt=0;
  for(int i=0;i<n;i++)
    if(is_intersected_ls(ps[i],ps[i+1],a,b))cnt++;
  
  return (cnt-cnt1)%2;
}

int crossPol(vector<point> pol1, vector<point> pol2){
  int szpol1=pol1.size();
  int szpol2=pol2.size();
  
  for(int i=0;i<szpol1;i++)
    if(inside(pol1[i],pol2))return 1;
  
  for(int i=0;i<szpol2;i++)
    if(inside(pol2[i],pol1))return 1;
  
  pol1.push_back(pol1[0]);
  pol2.push_back(pol2[0]);
  
  for(int i=0;i<szpol1;i++)
    for(int j=0;j<szpol2;j++)
      if(is_intersected_ls(pol1[i],pol1[i+1],pol2[j],pol2[j+1]))return 1;
  
  return 0;
}

int gr[101][101],fg[101],m;

void dfs(int j){
  fg[j]=1;
  for(int k=0;k<m;k++)
    if(gr[j][k]==1 && !fg[k])dfs(k);  
}

int main(void){
  int n;
  point a;
  vector<point>pol[101];
  
  while(cin >> n,n){
    
    for(int i=0;i<n;i++){
      cin >> m;
      
      for(int i=0;i<101;i++)pol[i].clear();
      
      for(int i=0;i<101;i++){
	for(int j=0;j<101;j++){
	  gr[i][j]=0;
	}
	fg[i]=0;
      }
      
      for(int j=0;j<m;j++){
	for(int k=0;k<4;k++){
	  cin >> a.x >> a.y;
	  pol[j].push_back(a);
	}
      }
      
      for(int j=0;j<m;j++){
	for(int k=0;k<m;k++){
	  if(j!=k && crossPol(pol[j],pol[k]))gr[j][k]=gr[k][j]=1;
	}
      }
      
      int cnt=0;
      for(int j=0;j<m;j++){
	if(fg[j]==0){
	  dfs(j);
	  cnt++;
	}
      }
      
      cout << cnt << endl;
    }
  }
  return 0;
}

Compiler output:
a.cc: In function 'int inside(point, std::vector<point>)':
a.cc:72:3: error: 'n' was not declared in this scope
   72 |   n=ps.size();
      |   ^