poj-1005 I Think I Need a Houseboat

原创于 2012-04-15 12:56:21 发布 · 610 阅读

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#each #integer #numbers #forms #input #扩展

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本文介绍了一个关于土地侵蚀预测的问题，通过计算特定坐标何时会被侵蚀进入逐年扩大的半圆区域。利用坐标位置计算对应的年份，采用简单的数学公式实现编程解答。

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                                                                                  I Think I Need a Houseboat
                                                                            Time Limit: 1000MS Memory Limit: 10000K
                                                                               Total Submissions: 68300 Accepted: 28812

Description

Fred Mapper is considering purchasing some land in Louisiana to build his house on. In the process of investigating the land, he learned that the state of Louisiana is actually shrinking by 50 square miles each year, due to erosion caused by the Mississippi River. Since Fred is hoping to live in this house the rest of his life, he needs to know if his land is going to be lost to erosion.

After doing more research, Fred has learned that the land that is being lost forms a semicircle. This semicircle is part of a circle centered at (0,0), with the line that bisects the circle being the X axis. Locations below the X axis are in the water. The semicircle has an area of 0 at the beginning of year 1. (Semicircle illustrated in the Figure.)

Input

The first line of input will be a positive integer indicating how many data sets will be included (N). Each of the next N lines will contain the X and Y Cartesian coordinates of the land Fred is considering. These will be floating point numbers measured in miles. The Y coordinate will be non-negative. (0,0) will not be given.
Output

For each data set, a single line of output should appear. This line should take the form of: “Property N: This property will begin eroding in year Z.” Where N is the data set (counting from 1), and Z is the first year (start from 1) this property will be within the semicircle AT THE END OF YEAR Z. Z must be an integer. After the last data set, this should print out “END OF OUTPUT.”
Sample Input

2
1.0 1.0
25.0 0.0
Sample Output

Property 1: This property will begin eroding in year 1.
Property 2: This property will begin eroding in year 20.
END OF OUTPUT.
Hint

1.No property will appear exactly on the semicircle boundary: it will either be inside or outside.
2.This problem will be judged automatically. Your answer must match exactly, including the capitalization, punctuation, and white-space. This includes the periods at the ends of the lines.
3.All locations are given in miles.
题意：说实话，这个英语看的我纠结呀。。。但，其实他要求的是什么呢？给出坐标（x轴上方的），一个半圆从原点开始，以每年50平方米的速度扩展（在x轴上方），求解在哪一年给出的坐标在这个半圆内。

坐标的x，y可以得到圆心在原点，过此点的圆的面积。那么，只要那个扩展的半圆面积大于此圆的面积的一半就ok咯。

#include<iostream>
using namespace std;
const double PI=3.1415926;
int main()
{
	int n;
	double x,y;
	while(cin>>n)
	{
		int i;
		for(i=1;i<=n;i++)
		{
			cin>>x>>y;
			cout<<"Property "<<i<<": This property will begin eroding in year "<<int(PI*(x*x+y*y)/100)+1<<"."<<endl;  //int(PI*(x*x+y*y)/100)这里只是去了商的整数部分，加1后就是答案了
		}
		cout<<"END OF OUTPUT."<<endl;
	}
	return 0;
}