39 lines
679 B
C++
39 lines
679 B
C++
#include<cstdio>
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#include<cmath>
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#include<algorithm>
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using namespace std;
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const int maxn=105;
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struct Node { double L,R; };
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inline bool operator<(const Node &a,const Node &b) { return a.L<b.L; }
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int n,R,res;
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Node a[maxn];
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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scanf("%d%d",&n,&R);
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for(int i=0;i<n;i++)
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{
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int x,y; scanf("%d%d",&x,&y);
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double t=sqrt(R*R-y*y);
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a[i].L=x-t; a[i].R=x+t;
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}
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sort(a,a+n);
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int q[maxn],cnt=0;
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for(int i=0;i<n;i++)
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{
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while(cnt>0&&a[q[cnt-1]].R>=a[i].R) cnt--;
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q[cnt++]=i;
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}
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double last=-10000000;
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for(int i=0;i<cnt;i++)
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if(a[q[i]].L>last)
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{
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res++;
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last=a[q[i]].R;
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}
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printf("%d\n",res);
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return 0;
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}
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