作者:
navystar
,
2023-05-25 21:13:18
,
所有人可见
,
阅读 9
//这里填你的代码^^
#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
const int N = 1e7 + 10;
int n, tt = 1;
int primes[N], cnt;
bool st[N];
inline void get(int x)
{
for (int i = 2; i <= x; i ++ )
{
if (!st[i]) primes[cnt ++] = i;
for (int j = 0; primes[j] * i <= x; j ++ )
{
st[primes[j] * i] = true;
if (i % primes[j] == 0) break;
}
}
}
inline void solve()
{
cin >> n;
int res = 0;
for (int i = 0; i < cnt; i ++ )
{
int a = primes[i];
if (a >= n) break;
if (!st[n - a] && a <= n - a) res ++;
}
cout << "Case " << tt ++ << ": " << res << endl;
}
int main()
{
cin.tie(nullptr) -> sync_with_stdio(0);
get(N);
int t = 1;
cin >> t;
while (t --) solve();
return 0;
}
//注意代码要放在两组三个点之间,才可以正确显示代码高亮哦~