mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
40 lines
787 B
C++
40 lines
787 B
C++
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#include <cstring>
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#include <cmath>
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#include <algorithm>
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#include <iostream>
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#include <cstdio>
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using namespace std;
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#define maxn 1000010
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bool prime[maxn];
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void Prime()
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{
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memset(prime,true,sizeof(prime));
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prime[0]=prime[1]=0;
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for(int i=2;i*i<maxn;i++)
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if(prime[i])
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for(int j=2*i;j<maxn;j+=i)
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prime[j]=0;
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}
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int main()
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{
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Prime();
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int n,ans,p;
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while(scanf("%d",&n)!=EOF)
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{
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ans=0;
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for(int i=1;;i++)
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{
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int tmp=3*i*i+3*i+1;
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if(tmp>n)
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break;
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if(prime[tmp])
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ans++;
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}
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if(ans)
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printf("%d\n",ans);
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else
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printf("No Special Prime!\n");
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}
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return 0;
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}
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