2812.txt

北大ACM题目例程 详细的解答过程 程序实现 算法分析

Problem Id:2812  User Id:fzk 
Memory:56K  Time:0MS
Language:G++  Result:Accepted

Source 

#include <stdio.h>


double x0, y0, xt, yt, x, y, v, area;

int main( ) {
	int n;
	while( 1 ) {
		scanf( "%d", &n );
		if( n < 3 )
			break;
		scanf( "%lf%lf", &xt, &yt );
		x0 = xt, y0 = yt;
		area = 0;
		
		while( --n ) {
			scanf( "%lf%lf", &x, &y );
			area += x*yt-xt*y;
			xt = x, yt = y;
		}
		area += x0*y - x*y0;
		if( area < 0 )
			area = -area;
		scanf( "%lf", &v );
		printf( "BAR LENGTH: %.2lf\n", 2*v/area );
	}
	return 0;
}