55 lines
1.0 KiB
C++
55 lines
1.0 KiB
C++
#include <iostream>
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#include <stdio.h>
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#include <cmath>
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#include <algorithm>
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#include <string.h>
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using namespace std;
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int L,d;
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struct I
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{
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double l,r;
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}inter[10000];
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bool cmp(I a ,I b)
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{
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if(a.r<b.r)
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return true;
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else if(a.r==b.r)
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{
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if(a.l>b.l)
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return true;
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return false;
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}
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return false;
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}
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int main()
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{
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double x,y;
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while(scanf("%d",&L)!=EOF)
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{
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scanf("%d",&d);
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int n;
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cin>>n;
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for(int i=1;i<=n;i++)
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{
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scanf("%lf%lf",&x,&y);
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inter[i].l=x-sqrt(d*d-y*y);
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inter[i].r=x+sqrt(d*d-y*y);
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}
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sort(inter+1,inter+1+n,cmp);
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int ans=1;
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double temp=inter[1].r;
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for(int i=2;i<=n;i++)
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{
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if(temp>L)
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temp=L;
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if(temp<inter[i].l)
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{
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ans++;
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temp=inter[i].r;
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}
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}
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cout<<ans<<endl;
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}
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return 0;
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}
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