NYOJ 题目12喷水装置（二）

#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
struct Point
{
	double x,r,x1,x2;
	int visit;
}p[10000];
bool cmp(struct Point a,struct Point b)
{
	return a.x1<b.x1||(a.x1==b.x1&&a.x2<b.x2);
}
int main()
{
	int n;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		int m;
		double len,wid;
		cin>>m>>len>>wid;
		double x,r;
		for(int j=0;j<m;j++)
		{
			cin>>x>>r;
			p[j].x=x;
			p[j].r=r;
			if(r<=wid/2)
			{p[j].visit=0;continue;}
			else
			{
				double d=sqrt(r*r-wid*wid/4);
				p[j].x1=x-d;
				p[j].x2=x+d;
				p[j].visit=1;
			}


		}
		sort(p,p+m,cmp);
		int a=0,b=0;
		int k=0;
		for(int j=0;j<m;j++)
		{
			if(p[j].visit)
			{
				if(p[j].x1<a)
					a=p[j].x1;
				if(p[j].x1<=b)
				{
					b=p[j].x2;
					k++;
					if(b>=len)
						break;
						
				}
			}
		}
		if(a<=0&&b>=len)
			cout<<k<<endl;
		else
			cout<<0<<endl;
		

	}
	return 0;

}