027.打印蛇形方阵

#include<stdio.h>
#define N 20
int main()
{
	int i, j, a[N][N], n, k;
	printf("请输入矩阵的阶:\n");
	scanf_s("%d",&n);
	k = 1;
	/*输出上三角*/
	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= i; j++)
		{
			if (i %2== 0)
			{
				a[i + 1 - j][j] = k;
			}
			else
			{
				a[j][i + 1 - j] = k;
			}
			k++;
		}
	}

	/*输出下三角*/
	for (i = n + 1; i < 2 * n; i++)
	{
		for (j = 1; j <= 2 * n - i; j++)
		{
			if (i % 2 == 0)
			{
				a[n + 1 - j][i - n + j] = k;
			}
			else
			{
				a[i - n + j][n + 1 - j] = k;
			}
			k++;
		}
	}
	printf("蛇形方针如下:\n");

	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= n; j++)
		{
			printf("%4d", a[i][j]);
		}
		printf("\n");
	}

	getchar();
	return 0;
}