66 lines
773 B
C++
66 lines
773 B
C++
#include <iostream>
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#include<cstdio>
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#include<algorithm>
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#include <cmath>
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#include <cstdlib>
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using namespace std;
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const int N=1e7+5,M=7e5+5;
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int pr[M];//´æÖÊÊý
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bool b[N];//ÊDz»ÊÇÖÊÊý
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int n;
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int n2;
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int t1=0,t;
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int cnt=0;
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int res;
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inline void prime()
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{
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for(int i=2;i<N;i++)
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{
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if(!b[i])
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{
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pr[++cnt]=i;
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}
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for(int j=1;j<=cnt&&pr[j]*i<N;j++)
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{
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b[pr[j]*i]=1;
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if(i%pr[j]==0)
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{
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break;
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}
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}
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}
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}
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//void ce()
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//{
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// cout<<cnt;
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// for(int i=1;i<=cnt;i++)
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// {
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// cout<<pr[i]<<" ";
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// }
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//}
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inline int doit()
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{
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res=0;
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n2=n/2;
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for(int i=1;pr[i]<=n2;i++)
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{
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if(!b[n-pr[i]])
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{
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res++;
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}
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}
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return res;
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}
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int main()
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{
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prime();
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// ce();
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scanf("%d",&t);
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while(t--)
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{
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scanf("%d",&n);
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printf("Case %d: %d\n",++t1,doit());
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}
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return 0;
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}
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