循环-04. 验证“哥德巴赫猜想”(20)

 1 #include<iostream>
 2 #include<cmath>
 3 using namespace std;
 4 bool isPrime(long n){
 5     int i;
 6     for(i=2;i<=sqrt(n);++i)
 7         if(n%i==0)
 8             break;
 9     if(n>1&&i>sqrt(n))
10         return true;
11     else
12         return false;
13 }
14 int main(){
15     long i,n;
16     cin>>n;
17     for(i=2;i<=n/2;++i)
18         if(isPrime(i)&&isPrime(n-i)){
19             cout<<n<<" = "<<i<<" + "<<n-i<<endl;
20             break;
21         }
22     return 0;
23 }