简单题
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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
#define N 1000005
bool is[N];
int prm[N];
int getprm(int n)
{
int i, j, k = 0;
int s, e = (int )(sqrt(0.0+n) +1);
memset(is, 1, sizeof(is));
prm[k++] = 2; is[0] = is[1] = 0;
for (i =4; i < n; i+= 2) is[i] = 0;
for(i = 3; i < e; i+=2)
if (is[i])
{
prm[k++] = i;
for(s = i * 2, j = i * i; j < n; j+=s)
is[j] = 0;
}
for(; i < n; i+=2)
if (is[i])prm[k++] = i;
return k;
}
int main()
{
//freopen("t.txt", "r", stdin);
int tot = getprm(1000000);
int n;
while (scanf("%d", &n), n)
{
for (int i = 0; i < tot && prm[i] * 2 <= n; i++)
if (is[n - prm[i]])
{
printf("%d = %d + %d\n", n, prm[i], n - prm[i]);
break;
}
}
return 0;
}