Print a matrix in spiral form.

Question: Write a program in C to print the given matrix in spiral order.

Input:
1    2    3    4
5    6    7    8
9   10   11  12
13  14  15  16
Output: 1 2 3 4 8 12 16 15 14 13 9 5 6  7 11 10

Printing a matrix in spiral order can be better understood by the following image.

Thus, printing a matrix in spiral order is just a way to traverse the matrix. The matrix can be supposed to be represented by a 2-D array.

#include<stdio.h>

void spiralPrint(int m, int n, int a[][n])
{
	int i,  k = 0, l = 0;
	m--, n--;

	while(k <= m && l <= n)
	{
		// Print the row left to right
		for(i = l; i <= n; ++i)
		{
			printf("%d ", a[k][i]);
		}

		// Print the column top to bottom
		k++;
		for(i = k; i <= m; ++i)
		{
			printf("%d ", a[i][n]);
		}

		// Print the row right to left
		n--;
		if(m >= k)
		{
			for(i = n; i >= l; --i)
			{
				printf("%d ", a[m][i]);
			}
			m--;
		}

		// Print the column bottom to top
		for(i = m; i >= k; --i)
		{
			printf("%d ", a[i][l]);
		}

		l++;
	}

	printf("\n");
}

int main(void)
{
	int arr[4][4] = {1, 2, 3, 4,
					5, 6, 7, 8,
					9, 10, 11, 12,
					13, 14, 15, 16};

	spiralPrint(4, 4, arr);

	return 0;
}