题解 | #查找组成一个偶数最接近的两个素数#

import java.util.Scanner;

/**
 * @author hll[yellowdradra@foxmail.com]
 * @since 2023-03-16 10:42
 **/
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        minDiff(in.nextInt());
    }

    public static void minDiff(int n) {
        for (int i = n >> 1; i > 0; i--) {
            if (isPrimeQuickly(i) && isPrimeQuickly(n - i)) {
                System.out.printf("%s\n%s\n", i, n - i);
                break;
            }
        }
    }

    public static boolean isPrimeQuickly(int n) {
        if (n == 2 || n == 3) {
            return true;
        }
        // 等价于 n % 2 == 0 即n是偶数
        if ((n & 1) == 0 || n <= 1) {
            return false;
        }
        int r = n % 6;
        if (r != 5 && r != 1) {
            return false;
        }
        int sqrt = (int) Math.sqrt(n);
        // 保证i为奇数
        for (int i = 5; i <= sqrt; i += 6) {
            if (n % i == 0 || n % (i + 2) == 0) {
                return false;
            }
        }
        return true;
    }
}