2017年藍橋杯第三題,答案144

package 藍橋杯;

public class Number2_2017 {
	
	static int[] a = {1,2,3,4,5,6,7,8,9};
	static int ans;
	
	public static void fun(int k) {
		
		
		 
		 if (k == 9) {
			 int x1 = a[0] + a[1] + a[3] + a[5];
			 int x2 = a[0] + a[2] + a[4] + a[8];
			 int x3 = a[5] + a[6] + a[7] + a[8];
			 if(x1 == x2 && x2 == x3) {
				 ans++;
			 }
		 }
		 //使用全排列
		 for(int i=k; i<9; i++) {
			 int t = a[k];
			 a[k] = a[i];
			 a[i] = t;
			 fun(k+1);
			 t = a[k];
			 a[k] = a[i];
			 a[i] = t;
		 }
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		fun(0);
		System.out.println(ans/6);
	}

}