poj1265 in e area

#include <iostream>
#include <cstdio>
#include <cstdlib>

#include <cmath>
using namespace std;


struct POINT
{
	int x,y;
}point[110];

int n;
double getArea()
{
	double sum = 0;
	for (int i = 0; i < n; ++ i)
	{
		sum += (point[i].x   * point[(i + 1) % n].y   - point[i].y  * point[(i + 1) % n].x );
	}
	return fabs(sum/2.0);
}

int Gcd(int a, int b)
{
	if (0 == b)
	{
		return a;
	}
	else
		return Gcd(b, a % b);
}
int getSegmentPoint(POINT p1, POINT p2)
{
	int a = abs(p2.y - p1.y);
	int b = abs(p2.x - p1.x);

	if (a == 0 && b == 0)
	{
		return 0;
	}
	if (a == 0)
	{
		return b - 1;
	}
	if (b == 0)
	{
		return a - 1;
	}
	return Gcd(b, a) - 1;
}
int getPoint()
{
	int ans = n;
	for (int i = 0; i < n; ++ i)
	{
		ans += getSegmentPoint(point[i], point[(i + 1) % n]);
	}
	return ans;
}
int main()
{
	int cas, j = 1;
	int temp1=0,temp2=0,temp3=0,temp4=0,begin1=0,begin2 = 0;
	scanf("%d", &cas);
	while (cas --)
	{
		scanf("%d", &n);
		point[0].x = point[0].y = 0;
	
		for (int i = 1; i <= n; ++ i)
		{
			scanf("%d %d", &point[i].x, &point[i].y);
			
		}
		for (int i = 1; i <= n; ++ i){
            point[i].x=point[i].x-point[n].x;
            point[i].y=point[i].y-point[n].y;
		}

		printf("Scenario #%d:\n", j ++);
		double Area = getArea();
		int res;
		int PointNum = getPoint();
		res = (int)Area - PointNum / 2 + 1;
		printf("%d %d %.1lf\n\n", res, PointNum, Area);
	}
	return 0;
}