1 #include<cmath>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<stdlib.h>
 5 #include<algorithm>
 6 using namespace std;
 7 int isprime(int num)
 8 {
 9     int k=sqrt(num),i;
10     for(i=2;i<=k;i++)
11     {
12         if(num%i==0)
13             break;
14     }
15     if(i>k)
16         return 1;
17     else
18         return 0;
19 }
20 int main()
21 {
22     //freopen("in.txt","r",stdin);
23     int n;
24     while(scanf("%d",&n)&&n)
25     {
26         int flag=0,ans;
27         for(int i=n-2;i>=0;i--)
28         {
29             if(isprime(i))
30             {
31                 ans=n-i;
32                 if(isprime(ans))
33                 {
34                     flag=1;
35                     printf("%d = %d + %d\n",n,ans,i);
36                     break;
37                 }
38             }
39         }
40         if(flag==0)
41             printf("Goldbach‘s conjecture is wrong.\n");
42     }
43     return 0;
44 }

 1 #include<cstdio>
 2 #include<cmath>
 3 #include<cstring>
 4 #include<stdlib.h>
 5 #include<algorithm>
 6 using namespace std;
 7 const int MAXN=1000000+10;
 8 const int N=999983;
 9 int prime[MAXN],vis[MAXN];
10 int cnt;
11 void init()//素数筛法
12 {
13     int i,j;
14     for(i=2;i<=N;i++)
15     {
16         if(i%2==0)
17             vis[i]=0;
18         else
19             vis[i]=1;
20     }
21     for(i=3;i<=sqrt(N);i+=2)
22     {
23         if(vis[i])
24             for(j=i+i;j<N;j+=i)
25                 vis[j]=0;
26     }
27     cnt=1;
28     prime[0]=2;
29     for(i=2;i<N;i++)
30         if(vis[i])
31             prime[cnt++]=i;
32 }
33 int main()
34 {
35     //freopen("in.txt","r",stdin);
36     init();
37     int n;
38     while(scanf("%d",&n)&&n)
39     {
40         int flag=0,ans;
41         for(int i=cnt-1;i>=0;i--)
42         {
43             if(prime[i]<n)
44             {
45                 ans=n-prime[i];
46                 if(binary_search(prime,prime+cnt,ans))
47                 {
48                     printf("%d = %d + %d\n",n,ans,prime[i]);
49                     flag=1;
50                     break;
51                 }
52             }
53         }
54         if(flag==0)
55             printf("Goldbach‘s conjecture is wrong.\n");
56     }
57     return 0;
58 }