Print matrix in antispiral form

https://www.geeksforgeeks.org/print-matrix-antispiral-form/

Given a 2D array, the task is to print matrix in anti spiral form:

Examples:

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

Input : arr[][4] = {1, 2, 3, 4
                    5, 6, 7, 8
                    9, 10, 11, 12
                    13, 14, 15, 16};
Output : 10 11 7 6 5 9 13 14 15 16 12 8 4 3 2 1

The idea is simple, we traverse matrix in spiral form and put all traversed elements in a stack. Finally one by one elements from stack and print them

    public static void antiSpiralTraversal(int m, int n, 

                                             int a[][])

    {

        int i, k = 0, l = 0;

       

        /*  k - starting row index

            m - ending row index

            l - starting column index

            n - ending column index

            i - iterator  */

        Stack<Integer> stk=new Stack<Integer>();

       

        while (k <= m && l <= n)

        {

            /* Print the first row from the remaining 

             rows */

            for (i = l; i <= n; ++i)

                stk.push(a[k][i]);

            k++;

       

            /* Print the last column from the remaining

            columns */

            for (i = k; i <= m; ++i)

                stk.push(a[i][n]);

            n--;

       

            /* Print the last row from the remaining 

            rows */

            if ( k <= m)

            {

                for (i = n; i >= l; --i)

                    stk.push(a[m][i]);

                m--;

            }

       

            /* Print the first column from the remaining 

            columns */

            if (l <= n)

            {

                for (i = m; i >= k; --i)

                    stk.push(a[i][l]);

                l++;

            }

        }

       

        while (!stk.empty())

        {

            System.out.print(stk.peek() + " ");

            stk.pop();

        }

https://stackoverflow.com/questions/35900519/inside-out-spiral-matrix-java
http://qa.geeksforgeeks.org/7017/qa.geeksforgeeks.org/7017/print-spiral-matrix-inside-out.html