【王道JAVA】【程序 44 偶數的素數和】

一個偶數（大於2）總能表示爲兩個素數之和。

import java.util.Scanner;

public class WangDao {
	public static void main(String[] args){
		System.out.print("Input a even number: ");
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		
		for (int i = 2; i <= n; i++) {
			for (int j = 2; j <= n; j++) {
				if (isPrime(i) && isPrime(j) && (i + j == n)) {
					System.out.println(n + " = " + i + "+" + j);
				}
			}
		}
	}
	
	public static boolean isPrime(int n) {
		boolean flag = true;
		
		if (n < 2) {
			flag = false;
		} else {
			for (int i = 2; i <= Math.sqrt(n); i++) {
				if (n % i == 0) {
					flag = false;
					break;
				}
			}
		}
		
		return flag;
	}
}