【喷水装置（二） 区间覆盖 贪心。】

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=12

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
struct point{
    double left,right;
}a[10001];
bool cmp(point b,point c){
    return b.left<c.left;
}
int main(){
    int ncase,n,len,wight;
    double w;
    scanf("%d",&ncase);
    while(ncase--){
        int flag=1,count=0;
        scanf("%d%d%d",&n,&len,&wight);
        w=wight/2.000000;
        for(int i=0;i<n;i++){
                int   xi,ri;
                double temp;
                scanf("%d%d",&xi,&ri);
                temp=sqrt(ri*ri-w*w);
                if(temp>0){
                    a[i].left=xi-temp;
                    a[i].right=xi+temp;
                }
        }
        sort(a,a+n,cmp);
        double max=0;
        double sum=0;
        while(sum<len){
            max=0;
            for( int i=0;i<n&&a[i].left<=sum;i++){
                    if(a[i].right-sum>max)
                         max=a[i].right-sum;
            }
             if(max==0){
                            flag=0;
                            break;
                    }
                    else{
                        count++;
                        sum+=max;
                    }
        }
        if(flag)
            printf("%d\n",count);
        else
            printf("0\n");
    }

}