OJ Board

Code: Select all

#include<cstdio>
#include<cmath>
struct point
{
	double x,y;
};

point p[10];
int n;

double area(point a,point b,point c)
{
	double area;

	area=a.x*(b.y-c.y)+b.x*(c.y-a.y)+c.x*(a.y-b.y);
	return 0.5*fabs(area);
}

int main()
{
	double sum,pt,r,t,total,pi=2*acos(0.0);
	int k;
//	freopen("in.in","r",stdin);
	while(scanf("%d",&n)==1 && n)
	{
		total=0;
		for(k=0;k<n;k++)
		{
			scanf("%lf%lf%lf%lf%lf",&pt,&p[0].x,&p[0].y,&p[1].x,&p[1].y);

			sum=0;
			while(scanf("%lf%lf",&p[2].x,&p[2].y) && (p[2].x!=p[0].x || p[2].y!=p[0].y))
			{
				sum+=area(p[0],p[1],p[2]);
				p[1]=p[2];
			}

			total+=pt*sum;
		}
		scanf("%lf%lf",&r,&t);
		printf("%.0lf\n",floor(total/(pi*r*r*t)));
	}
	return 0;
}

Code: Select all

 
(x1y2 + x2y3 + x3y4 + ............. + xny1) - (y1x2 + y2x3 + y3x4 +.......... ynx1)

Code: Select all

#include <stdio.h>
#include <string.h>
#include <math.h>

#define pi acos(-1)

char Table[100024];
double x[20005];
double y[20005];

int main() {

	int i, j;
	int N;
	
	//freopen("D:\\in.txt", "r", stdin);
	while (scanf("%d", &N) == 1) {
		if (N == 0) break;

		gets(Table);
		double ans1 = 0, ans2 = 0, ans = 0;
		for (j = 1; j <= N; j++) {
			gets(Table);
			
			char *p;
			p = strtok(Table, " ");
			int n = 1;
			int m = 1;
			double t;
			sscanf(p, "%lf", &t);
			while (1) {
				p = strtok(NULL, " ");
				if (p == NULL) break;
				sscanf(p, "%lf", &x[n++]);
				p = strtok(NULL, " ");
				sscanf(p, "%lf", &y[m++]);
			}
			ans1 = ans2 = 0.0;			
			for (i = 1; i < n - 1; i++) {
				ans1 += ((x[i] * y[i + 1]) - (y[i] * x[i + 1]));
			}
			ans1 += ((x[n] * y[1]) - (y[n] * x[1]));
			
			ans += fabs(0.5 * (ans1) * t);
		}
		double area;
		double r, s;
		scanf("%lf %lf", &r, &s);
		area = 1.0 * s * pi * r * r;
		printf("%.0lf\n", floor(ans / area + .5));
	}
	return 0;
}