Print a given matrix in spiral form

Given a 2D array, print it in spiral form. See the following examples.

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 


Input:
        1   2   3   4  5   6
        7   8   9  10  11  12
        13  14  15 16  17  18
Output: 
1 2 3 4 5 6 12 18 17 16 15 14 13 7 8 9 10 11

Solution:

/* This code is adopted from the solution given    @ http://effprog.blogspot.com/2011/01/spiral-printing-of-two-dimensional.html */   #include <stdio.h> #define R 3 #define C 6   void spiralPrint(int m, int n, int a[R][C]) {     int i, k = 0, l = 0;       /*  k - starting row index         m - ending row index         l - starting column index         n - ending column index         i - iterator     */       while (k < m && l < n)     {         /* Print the first row from the remaining rows */         for (i = l; i < n; ++i)         {             printf("%d ", a[k][i]);         }         k++;           /* Print the last column from the remaining columns */         for (i = k; i < m; ++i)         {             printf("%d ", a[i][n-1]);         }         n--;           /* Print the last row from the remaining rows */         if ( k < m)         {             for (i = n-1; i >= l; --i)             {                 printf("%d ", a[m-1][i]);             }             m--;         }           /* Print the first column from the remaining columns */         if (l < n)         {             for (i = m-1; i >= k; --i)             {                 printf("%d ", a[i][l]);             }             l++;            }            } }   /* Driver program to test above functions */ int main() {     int a[R][C] = { {1,  2,  3,  4,  5,  6},         {7,  8,  9,  10, 11, 12},         {13, 14, 15, 16, 17, 18}     };       spiralPrint(R, C, a);     return 0; }   /* OUTPUT:   1 2 3 4 5 6 12 18 17 16 15 14 13 7 8 9 10 11 */

Time Complexity: Time complexity of the above solution is O(mn).

Please write comments if you find the above code incorrect, or find other ways to solve the same problem.