Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"strings"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		input := strings.Split(scanner.Text(), " ")
		buf := make([]float64, len(input))
		for j := range buf {
			buf[j], _ = strconv.ParseFloat(input[j], 64)
		}
		p1 := complex(buf[0], buf[1])
		p2 := complex(buf[2], buf[3])
		p3 := complex(buf[4], buf[5])
		pk := complex(buf[6], buf[7])
		ps := complex(buf[8], buf[9])
		kin := isAtSameSide(p3, pk, []complex128{p1, p2}) &&
			isAtSameSide(p1, pk, []complex128{p2, p3}) &&
			isAtSameSide(p2, pk, []complex128{p3, p1})
		sin := isAtSameSide(p3, ps, []complex128{p1, p2}) &&
			isAtSameSide(p1, ps, []complex128{p2, p3}) &&
			isAtSameSide(p2, ps, []complex128{p3, p1})
		if (kin || sin) && !(kin && sin) {
			fmt.Println("OK")
		} else {
			fmt.Println("NG")
		}
	}
}

func isAtSameSide(a, b complex128, line []complex128) bool {
	sa := (real(line[1]) - real(line[0]))*(imag(a)-imag(line[0]))+
		(imag(line[1])-imag(line[0]))*(real(line[0])-real(a))
	sb := (real(line[1]) - real(line[0]))*(imag(b)-imag(line[0]))+
		(imag(line[1])-imag(line[0]))*(real(line[0])-real(b))
	return (sa > 0 && sb > 0) || (sa < 0 && sb < 0)
}

C++: #include <cmath>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
class Point {
public:
	long double px, py;
	Point() : px(0), py(0) {};
	Point(long double px_, long double py_) : px(px_), py(py_) {};
	bool operator==(const Point& p) const { return px == p.px && py == p.py; }
	bool operator!=(const Point& p) const { return px != p.px || py != p.py; }
	bool operator<(const Point& p) const { return px < p.px ? true : (px == p.px && py < p.py); }
	bool operator>(const Point& p) const { return px > p.px ? true : (px == p.px && py > p.py); }
	bool operator<=(const Point& p) const { return !(Point(px, py) > p); }
	bool operator>=(const Point& p) const { return !(Point(px, py) < p); }
	Point operator+(const Point& p) const { return Point(px + p.px, py + p.py); }
	Point operator-(const Point& p) const { return Point(px - p.px, py - p.py); }
	Point operator/(long double d) const { return Point(px / d, py / d); }
	friend Point operator*(const Point p, long double d) { return Point(p.px * d, p.py * d); }
	friend Point operator*(long double d, const Point& p) { return p * d; }
	Point& operator+=(const Point& p1) { px += p1.px, py += p1.py; return *this; }
	Point& operator-=(const Point& p1) { px -= p1.px, py -= p1.py; return *this; }
	Point& operator*=(long double d) { px *= d, py *= d; return *this; }
	Point& operator/=(long double d) { px /= d, py /= d; return *this; }
};
long double norm(const Point& a) { return a.px * a.px + a.py * a.py; }
long double abs(const Point& a) { return sqrtl(norm(a)); }
long double arg(const Point& a) { return atan2l(a.py, a.px); }
long double dot(const Point& a, const Point& b) { return a.px * b.px + a.py * b.py; }
long double crs(const Point& a, const Point& b) { return a.px * b.py - a.py * b.px; }
int contain(vector<Point> v, Point p) {
	bool in = false;
	for (int i = 0; i < v.size(); ++i) {
		Point a = v[i] - p, b = v[(i + 1) % v.size()] - p;
		if (a.py > b.py) swap(a, b);
		if (a.py <= 0 && 0 < b.py)
			if (crs(a, b) < 0) in = !in;
		if (crs(a, b) == 0 && dot(a, b) <= 0) return 1;
	}
	return in ? 2 : 0;
}
int n; Point a, b;
int main() {
	cin >> n;
	for (int i = 0; i < n; i++) {
		vector<Point> v(3);
		for (int j = 0; j < 3; j++) cin >> v[j].px >> v[j].py;
		cin >> a.px >> a.py >> b.px >> b.py;
		if (contain(v, a) != contain(v, b)) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<vector>
using namespace std;

struct point{
	double x, y;
};

vector<point> t(3);

bool isIn(point s) {
	point a, b, c;
	a.x = t[1].x-t[0].x; a.y = t[1].y-t[0].y;
	b.x = t[2].x-t[0].x; b.y = t[2].y-t[0].y;
	c.x = s.x-t[0].x; c.y = s.y-t[0].y;
	double c1, c2;
	c1 = (b.y*c.x - b.x*c.y) / (a.x*b.y - a.y*b.x);
	c2 = (a.y*c.x - a.x*c.y) / (a.y*b.x - a.x*b.y);
	if ((c1>0.0)&&(c2>0.0)&&(c1+c2<1.0)) return true;
	return false;
}

int main()
{
	int n, i;
	point s, g;
	cin>>n;
	for (i = 0; i < n; i++) {
		cin>>t[0].x>>t[0].y>>t[1].x>>t[1].y>>t[2].x>>t[2].y;
		cin>>s.x>>s.y>>g.x>>g.y;
		if (isIn(s)^isIn(g)) cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
	}
	return 0;
}

C++: #include<cmath>
#include<algorithm>
#include<iostream>
#include<vector>
#include<climits>
#include<cfloat>
 
using namespace std;
 
double EPS = 1e-10;
 
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);
  }
};
 
struct segment{
  point a,b;
};
 
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_intersected_ls(point a1, point a2, point b1, point b2) {
  return ( cross(a2-a1, b1-a1) * cross(a2-a1, b2-a1) < EPS ) &&
         ( cross(b2-b1, a1-b1) * cross(b2-b1, a2-b1) < EPS );
}

 double vec_abs(point a){
  return sqrt(a.x*a.x+a.y*a.y);
}

int ccw(point p0, point p1, point p2){
  point a = p1 - p0;
  point b = p2 - p0;
  if(cross(a,b)>EPS)return +1;
  if(cross(a,b)<EPS)return -1;
  if(dot(a,b)<-EPS)return +2;
  if(a.x*a.x+a.y*a.y<b.x*b.x+b.y*b.y)return -2;
  return 0;
}

int is_point_on_line(point a, point b, point c) {
  return (vec_abs(a-c) + vec_abs(c-b) < vec_abs(a-b) + EPS);
}

int inside(point p, point* ps, int n){
  segment t;
  t.a=t.b=p;
  t.b.x=INT_MAX;

  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(t.a.y<=ymn+EPS||t.a.y>=ymx-EPS)return 0;

  int cnt1=0,cnt2=0;
  for(int i=0;i<n;i++){
    if(is_point_on_line(t.a,t.b,ps[i])){
      cnt1++;
      continue;
    }
    if(is_intersected_ls(ps[i],ps[i+1],t.a,t.b))cnt2++;
  }
  return ((cnt1/2)+cnt2)%2;
}

int main(void){
  int n;
  point p[5],k,s;
 
  cin >> n;
  while(n--){

    for(int i=0;i<3;i++)
      cin >> p[i].x >> p[i].y;
     
    cin >> k.x >> k.y >> s.x >> s.y;
 
    if(inside(k,p,3)!=inside(s,p,3))cout << "OK" << endl;
    else cout << "NG" << endl;
     
  }
 
  return 0;
}