奇数阶魔方阵

#include <stdio.h>

int main(void)
{
	static int a[21][21], i, j, n;
	int k;

	scanf("%d", &n);
	j = n / 2 + 1; i = 1;
	a[i][j] = 1; 	
	for (k = 2; k <= n * n; k++)
	{
		if ((a[i - 1][j + 1] != 0) || (i - 1 == 0) && (j + 1 == n + 1))
		{
			j; i += 1;
		}
		else
		{
			i--; j++;
			if (i == 0) i = n;
			if (j == n + 1) j = 1;
		}
		a[i][j] = k;
	}
	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= n; j++)
			printf("%d\t", a[i][j]);
		printf("\n");
	}
	return 0;
}