Chapter Pointer Question 7

topic:

Write a function to generate magic array. The parameter of the function is the order of the generated magic array, and the returned value is the generated magic array.

(The N-order magic array is an N*N matrix composed of natural numbers between 1 and N*N, where N is an odd number. The sum of each row, column and diagonal is equal.)

Code:

#include <iostream>
using namespace std;

void function(int n);

int main()
{
	cout << "生成一个魔阵" << endl << endl;
	
	int n;
	cout << "请输入生成的魔阵的阶数：（必须为奇数）";
	cin >> n;

	function(n);
	
	system("pause");
	return 0;
}

void function(int n)
{
	if (n % 2 == 0) cout << endl << "错误！" << n << "为偶数！" << endl << endl;
	else
	{
		int **a, i = 0, j, k;
		a = new int *[n];
		for (i = 0; i < n; ++i) a[i] = new int[n];

		for (i = 0; i < n; ++i)
		{
			for (j = 0; j < n; ++j)
			{
				a[i][j] = 0;
			}
		}

		//填写方法：
		j = (n - 1) / 2;
		a[0][j] = 1;   //1.第一个元素放在第一行中间一列

		for (k = 2; k <= n*n; ++k)
		{
			//注意从除法的角度理解下面的特殊情况

			//2.下一个元素存放在当前元素的上一行、下一列
			if (a[(i - 1 + n) % n][(j + 1) % n] == 0)
			{
				i = (i - 1 + n) % n;
				j = (j + 1) % n;
				a[i][j] = k;
			}

			//3.若上一行、下一列已经有内容，则下一个元素的存放位置为当前列的下一行
			else
			{
				i = (i + 1) % n;
				a[i][j] = k;
			}
		}

		cout << endl << n << "阶魔阵为：";
		for (i = 0; i < n; ++i)
		{
			cout << endl;
			for (j = 0; j < n; ++j)
			{
				if ((a[i][j] >= 1) & (a[i][j] <= 9)) cout << " ";
				cout << a[i][j] << "  ";
			}
		}
		cout << endl << endl;
	}
}