UVA 543 - Goldbach's Conjecture

 /* use seive method to generate the table of prime number 
    reference: http://www.cnblogs.com/xiaobaibuhei/p/3329702.html
    http://maplewing.blogspot.tw/2011/02/uva543goldbachs-conjecture.html*/
  
 #include <iostream>
 #include <vector>
 #include <bitset>
 #define MAX 1000000
 using namespace std;
 
 bitset<MAX+1> bs;
 vector<int> primes;
   
 void seive(){
   bs.set(); // set all bit to 1
   bs[0]=false, bs[1]=false;
 
   for (long long int i=2; i<=MAX; ++i){
     if (bs[i]==true){
       for (long long int j=i*i; j<=MAX; j+=i)
         bs[j]=false;
       primes.push_back(i);
     }
   }
   return;
 }
 
 int main(int argc, char *argv[]){
   seive();
   int n;
   while(cin>>n && n){
     for (int i=0; i<primes.size(); ++i){
       if (bs[primes[i]]==true && bs[n-primes[i]]==true){
         cout << n << " = " << primes[i] << " + " << n-primes[i] << endl;
         break;
       }
     }
   }
   return 0;
}