ZOJ 1951 Goldbach's Conjecture(素数打表)

#include <cstdio>  #include <iostream>  #include <cmath>  using namespace std;  const int maxn=1000010;  bool isP[maxn];  int n; void init(){ for(int i=2;i<maxn;++i){  isP[i]=1;  }  for(int i=2;i<maxn;++i){  if(isP[i]){  for(int j=2;j*i<maxn;++j){  isP[i*j]=0;  }  }  }  }  int main(){  init();  while(scanf("%d",&n)&&n){  int i;  for(i=3;i<=n;++i){  if(isP[i]&&isP[n-i]){  break;  }  } printf("%d = %d + %d\n",n,i,n-i);}  return 0;  }