Java Program to Print matrix in antispiral form

// Java Code for Print matrix in antispiral form
import java.util.*;

class GFG {
    
    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();
        }
    }
    
    /* Driver program to test above function */
    public static void main(String[] args) 
    {
         int mat[][] =
                {
                    {1,  2,  3,  4,  5},
                    {6,  7,  8,  9,  10},
                    {11, 12, 13, 14, 15},
                    {16, 17, 18, 19, 20}
                };
             
        antiSpiralTraversal(mat.length - 1, mat[0].length - 1, 
                                                       mat);
    }
  }
// This code is contributed by Arnav Kr. Mandal.