Go: package main

import "fmt"

func main() {
	var x1, x2, x3, y1, y2, y3, xp, yp float64
	for {
		v, _ := fmt.Scanf("%f %f %f %f %f %f %f %f", &x1, &y1, &x2, &y2, &x3, &y3, &xp, &yp)
		// println(x1, x2, x3, y1, y2, y3, xp, yp)
		if v != 8 {
			break
		}
		ok1 := true
		ok2 := true
		if (x2-x1)*(yp-y1)-(xp-x1)*(y2-y1)<0 {
			ok1 = false
		} else {
			ok2 = false
		}
		if (x3-x2)*(yp-y2)-(xp-x2)*(y3-y2)<0 {
			ok1 = false
		} else {
			ok2 = false
		}
		if (x1-x3)*(yp-y3)-(xp-x3)*(y1-y3)<0 {
			ok1 = false
		} else {
			ok2 = false
		}
		if ok1 || ok2 {
			fmt.Println("YES")
		} else {
			fmt.Println("NO")
		}
	}
}

C++: #include<algorithm>
#include<cassert>
#include<climits>
#include<cmath>
#include<cstring>
#include<deque>
#include<functional>
#include<iomanip>
#include<iostream>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<vector>

using namespace std;

using lint = long long;
using P = pair<int, int>;
using LLP = pair<long long, long long>;

#define REP(i, x, n) for(int i = (x), i##_len = int(n) ; i < i##_len ; ++i)
#define rep(i, n) for(int i = 0, i##_len = int(n) ; i < i##_len ; ++i)
#define reps(i, n) for(int i = 1, i##_len = int(n) ; i <= i##_len ; ++i)
#define rrep(i, n) for(int i = int(n) - 1 ; i >= 0 ; --i)
#define rreps(i, n) for(int i = int(n) ; i > 0 ; --i)
#define SORT(x) sort((x).begin(), (x).end())
#define SORT_INV(x) sort((x).rbegin(), (x).rend())
#define TWINS(x) cout << ((x) ? "Yay!" : ":(") << endl

constexpr int IINF = (1 << 30) - 1;
constexpr long long LLINF = 1LL << 61;
constexpr double EPS = 1e-8;

const int dx4[] = {1, 0, -1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dy8[] = {0, -1, -1, -1, 0, 1, 1, 1};

template<typename T>
bool chmax(T &a, T b){
    if(a < b){
        a = b;
        return true;
    }
    return false;
}

template<typename T>
bool chmin(T &a, T b){
    if(b < a){
        a = b;
        return true;
    }
    return false;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    double x1, y1, x2, y2, x3, y3, xp, yp;
    while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> xp >> yp){
        double x = 0.5 * (-y1 * x2 + y3 * (x2 - x1) + x3 * (y1 - y2) + x1 * y2);
        double s = 1.0 / (2.0 * x) * (y3 * x2 - x3 * y2 + (y2 - y3) * xp + (x3 - x2) * yp);
        double t = 1.0 / (2.0 * x) * (x3 * y1 - y3 * x1 + (y3 - y1) * xp + (x1 - x3) * yp);
        if(0.0 < s && s < 1.0 && 0.0 < t && t < 1.0 && 0.0 < 1.0 - s - t && 1.0 - s - t < 1.0){
            cout << "YES" << endl;
        }else{
            cout << "NO" << endl;
        }
    }

    return 0;
}

C++: #include <iostream>
using namespace std;
double x[4],y[4],px,py,ax,ay,bx,by;
int main()
{
	while(true)
	{
		for(int i = 1;i<=3;i++){cin >> x[i];cin >> y[i];}
		if(cin.eof())break;
		cin >> px;
		cin >> py;
		double m,n;
		ax = x[2]-x[1];
		ay = y[2]-y[1];
		bx = x[3]-x[1];
		by = y[3]-y[1];
		double det = ax*by-ay*bx;
		m = (by*px-bx*py)/det;
		n = (-ay*px+ax*py)/det;
		if(m>0 && m <1&& n > 0 && n < 1&& m*m+n*n < 1) cout << "YES" << endl;
		else cout << "NO" << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define INF INT_MAX/3
#define ALL(a) (a).begin(),(a).end()
#define CLR(a) memset(a,0,sizeof(a))

typedef long long int ll;

using namespace std;

int main(){

    double x[4],y[4];
    while(true){
	REP(i,4) {
	    cin >> x[i];
	    if(cin.eof()) return 0;
	    cin >> y[i];
	}
	double s,t;
	double m = 0;
	bool flg = false;
	    double x1[] =  {x[2] - x[0],  x[1] - x[0]};
	    double y1[] = { y[2] - y[0] , y[1] - y[0]};
	    double x2 = x[3] - x[0];
	    double y2 = y[3] - y[0];
	    REP(i,1e3){
		REP(j,1e3){
		s = (double)i / 1e3;
		t = (double)j / 1e3;
		if(s * x1[0] + t * x1[1] - x2 < 1e-3 && s * y1[0] + t * y1[1] - y2 < 1e-3){
		    flg = true;
		    break;
		}
	    }
		if(flg) break;
	    }
	    if(flg) cout << "YES" << endl;
	    else cout << "NO" << endl;

    }

    return 0;
}

C++: #include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <complex>
#include <ctime>
#include <cstdlib>

using namespace std;

inline int to_int(string s) {int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string to_str(T x) {ostringstream sout; sout << x; return sout.str();}

typedef long long ll;

int main()
{
	double x[4], y[4], xp, yp;
	double vx, vy, vpx, vpy;
	double crossZ;
	while(scanf("%lf%lf%lf%lf%lf%lf%lf%lf", &x[0], &y[0], &x[1], &y[1], &x[2], &y[2], &xp, &yp) != EOF)
	{
		bool ans = true;
		x[3] = x[0]; y[3] = y[0];
		for(int i = 0; i < 3; i++)
		{
			vx = x[i+1] - x[i];
			vy = y[i+1] - x[i];
			vpx = xp - x[i];
			vpy = yp - y[i];

			crossZ = vx * vpy - vy * vpx;
			printf("%lf\n", crossZ);
			if(crossZ < 0)
			{
				ans = false;
				break;
			}
		}
		cout << (ans?"YES":"NO") << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

#define fs first
#define sc second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define pb emplace_back

using pii = pair<int, int>;
using vi = vector<int>;
using lint = long long;

const int inf = 1001001001;
const lint linf = 1001001001001001001ll;
const int mod = 1e9 + 7;
const int dx[]{0, 1, 0, -1, -1, -1, 1, 1}, dy[]{1, 0, -1, 0, -1, 1, -1, 1};

template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; } return a > b; }
template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; } return a < b; }
template<typename T> inline void print(const T &x, string s = "\n") { cout << x << s; }
template<typename T> inline void print(const vector<T> &v, string s = " ") 
{ rep(i, v.size()) cout << v[i] << (i + 1 == v.size() ? "\n" : s); }
inline bool inside(int y, int x, int H, int W) { return 0 <= y && y < H && 0 <= x && x < W; }
inline lint in() { lint x; std::cin>>x; return x; }

#define X real()
#define Y imag()
typedef complex<double> P;
const double EPS = 1e-10;

double cross(P a, P b) {
	return (a.real() * b.imag() - a.imag() * b.real());
}

bool is_intersected(P a1, P a2, P b1, P b2) {
	return ( cross(a2-a1, b1-a1) * cross(a2-a1, b2-a1) < -EPS ) &&
		( cross(b2-b1, a1-b1) * cross(b2-b1, a2-b1) < -EPS );
}

int main() {
	double latte[4], beet[4];
	while (cin >> latte[0]) {
		rep(i, 4) {
			if (i == 0) cin >> beet[0];
			else cin >> latte[i] >> beet[i];
		}

		P a[3], r;

		rep(i, 3) {
			a[i] = P(latte[i], beet[i]);
		}

		r = P(latte[3], beet[3]);

		int ans = 1;
		int cnt = 0;
		rep(_, 4) {
			rep(i, 3) {
				cnt += is_intersected(a[i], a[(i + 1) % 3], r, P(100.1 * (_ & 2 ? 1 : -1), 100.1 * (_ & 1 ? 1 : -1)));
			}
			ans *= cnt;
		}

		cout << (ans ? "YES" : "NO") << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

double x[4], y[4];

double l(int a, int b)
{
	return sqrt((y[a] - y[b]) * (y[a] - y[b]) + (x[a] - x[b]) * (x[a] - x[b]));
}

double T(int a, int b, int c)
{
	double A = l(a, b);
	double B = l(b, c);
	double C = l(c, a);
	double s = (A + B + C) / 2;
	return sqrt(s * (s - A) * (s - B) * (s - C));
}

int main()
{
	while (true){
		for (int i = 0; i < 4; i++){
			if (scanf("%lf %lf", &x[i], &y[i]) == EOF) return 0;
		}
		
		double S = T(0, 1, 3) + T(1, 2, 3) + T(2, 0, 3) - T(0, 1, 2);
		
		if (S == 0){
			puts("YES");
		}
		else {
			puts("NO");
		}
	}
	
	return 0;
}