poj: 2262

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <string>
 4 #include <stack>
 5 #include <map>
 6 #include <vector>
 7 #include <algorithm>
 8 using namespace std;
 9 
10 bool isPrime(int n) {
11     if (n == 2) return true;
12     if (n % 2 == 0 || n == 1) return false;
13     for (int i = 3; i*i <= n; ++i) {
14         if (n % i == 0) return false;
15     }
16     return true;
17 }
18 
19 int main()
20 {
21     int N;
22     while (cin >> N && N) {
23         bool flag = false;
24         for (int i = 3; i <= N/2; i+=2) {
25             if (isPrime(i) && isPrime(N-i)) {
26                 flag = true;
27                 cout << N << " = " << i << " + " << N-i << endl;
28                 break;
29             }
30         }
31         if (!flag) cout << "Goldbach‘s conjecture is wrong." << endl;
32     }
33 
34     return 0;
35 }