2183.cpp

这是哈尔滨工业大学acmOJ的源代码

/*  This Code is Submitted by wywcgs for Problem 2183 on 2006-03-27 at 11:14:08 */ 
#include <cstdio>
#include <cmath>

const int MAX = 102400;

int main()
{
	int i, n;
	double x[MAX], y[MAX];
	
	while(scanf("%d", &n) != EOF && n >= 3) {
		for(i = 0; i < n; i++) scanf("%lf %lf", &x[i], &y[i]);
		x[n] = x[0]; y[n] = y[0];
		double area = 0, volume;
		for(i = 0; i < n; i++) area += x[i]*y[i+1] - x[i+1]*y[i];
		scanf("%lf", &volume);
		printf("BAR LENGTH: %.2lf\n", volume*2/fabs(area));
	}
	
	return 0;
}