2262.cpp

这些是我到目前在PKU上做出的题目

#include <iostream.h>
int main()
{int n,i,j;
 bool a[1000001];
 for (i=2;i<=1000000;i=i+2) a[i]=0;
 for (i=3;i<=1000000;i=i+2) a[i]=1;
 a[2]=1;
 for (i=3;i<=500000;i=i+2) 
  if (a[i]==1) for (j=i+i;j<=1000000;j=j+i) a[j]=0;
 cin>>n;
 while (n!=0)
 {i=2;
  while (a[i]!=1 || a[n-i]!=1) i++;
  cout<<n<<" = "<<i<<" + "<<n-i<<"\n";
  cin>>n;}
return 0;}