[Silver 2] 17103번 골드바흐 파티션

import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(br.readLine());
        
        while(t-- > 0) {
            int n = Integer.parseInt(br.readLine());
            int count = 0;
            boolean[] prime = new boolean[n+1];
            prime = prime(prime, n);

            for(int i=2; i<=(n+1)/2; i++) {
                if(!prime[i] && !prime[n-i]) {
                    count++;
                }
            }
            
            System.out.println(count);
        }
    }
    
    public static boolean[] prime(boolean[] prime, int n) {
        prime[0] = true;
        prime[1] = true;
        
        for(int i=2; i*i<=n; i++) {
            if(!prime[i]) {
                for(int j=i*i; j<=n; j+=i) {
                    prime[j] = true;
                }
            }
        }
        
        return prime;
    }
}