I Think I Need a Houseboat 1005 PKU

description：

某个地方被Mississippi河腐蚀每年都会有50square miles，而且总共腐蚀是个半圆，求给定一个点什么时候会被腐蚀

solution：

求该点到（0，0）的长度r，求以r为半径半圆的面积area，除以50即可得到答案

1. 一个难点是浮点型精度的处理，但是好像多想了，题目给出HINT：No property will appear exactly on the semicircle boundary: it will either be inside or outside.

#include <stdio.h>

#define PI 3.1415926535
#define EPS 1e-6

int main()
{
int cases=0,i=0;
double year=0;
double area=0,x=0,y=0;

scanf ("%d",&cases);

for (i=1; i<=cases; i++)
{
scanf ("%lf %lf",&x,&y);
area = (x*x+y*y)*PI/2;

year = area / 50;
printf ("Property %d: This property will begin eroding in year %d.\n",
i,(int)(year-EPS)+1);
}

printf("END OF OUTPUT.\n");

return 0;
}