【周练】 物理题

物理题 Crawling in process... Crawling failed

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u

Description

Come back school from the 33 rdACM / ICPC Asia ChenDu, everyone is exhausted, in particular the captain Wiskey. As saying that night, Wiskey drink a lot of wine, just as he blurred, fall to sleep. All of a sudden, Wiskey felt a slight discomfort in the chest, and then vomiting, vomitted all over. The next day, Wiskey is extremely sluggish, vomit still on the train. Your task is to calculate the coordinates of vomit. We assume that the quality of vomit is m, and its size can be ignored. As the figure below:

The vomit start from the blue point A, whose speed is V, and its angle with X-axis is a. If the vomit hit the ceiling, then its value of the speed don't changed and if before the collision the angle of the speed with X-axis is b, then after the collision the angle of the speed with X-axis is b , too. Ignore air resistance, acceleration due to gravity g = 9.87m/s 2, calculate and output Q. (you can assume that the vomit will not fall to the higher berth)

Input

Each line will contain three numbers V , m and a (0 <= a < 90)described above. Process to end of file.

Output

For each case, output Q in one line, accurate up to 3 decimal places.

Sample Input

100 100 45 

Sample Output

3.992 

室友和我一致吐槽：好恶心！！！用个小球也好啊，非得弄个呕吐物。就当复习高中物理吧，比较爽的是，高中需要算半天，现在只需要写代码，省事多了！

代码如下：

#include <stdio.h>
#include <math.h>
#define PI 3.1415926
#define g 9.87
int main()
{
	double v,m,a;
	double vx,vy;		//正交分解 
	double h1,h2;
	double t,t1,t2;		//总时间，上升时间，下落时间
	double Q;
	while (~scanf ("%lf%lf%lf",&v,&m,&a))
	{
		h1=0.5;
		h2=3;
		a=a/180*PI;
		vx=v*cos(a);
		vy=v*sin(a);
		if (vy*vy/(2*g)<=h1)
		{
			t1=vy/g;
			h2=h2+(vy*vy/2/g);
			t2=sqrt(2*h2/g);
			t=t1+t2;
			Q=t*vx;
			printf ("%.3lf\n",Q);
		}
		else
		{
			double vv;		//反弹时y轴速度 
			vv=sqrt(vy*vy-2*g*h1);
			h2=3.5;
			t1=(vy-vv)/g;
			t2=(-2*vv+sqrt(4*vv*vv+8*g*h2))/2/g;
			t=t1+t2;
			Q=t*vx;
			printf ("%.3lf\n",Q);
		}
	}
	return 0;
}