Puzzle 29 – Solution.

The trick here is to control a for loop using multiple variables. Thus a single for loop can be used as multiple for loop.
The code expalins this principle –

package com.twister;
import java.util.Scanner;
class Matrix{

 public static void main(String a[])
 {
     int r,c;
     int i,j,k=0;
     int matrix[][]  = new int[10][10];
     r = 2;    c= 2;

     /*Variable k is used to determine whether the for Loop
       is currently scanning elements or printing them
       k = 0  Loop is in scan mode
       k = 1 Loop is in print mode
      */
     for(j=0,i=0;i<r && j<c && k!=2;j++){
         if(k==0)    //Scan mode
                matrix[i][j] = new Scanner(System.in).nextInt(); 

         if(k==1)    //Print Mode
                System.out.print(matrix[i][j]+ " ");

         if(i==r-1 && j==c-1){    //Swap from scan mode to print mode
                k++;
             i=0;j=-1;
         }

         if(j==(c-1)){
             j=-1;i++;
             if(k==1)
                 System.out.println("");    //Prints a Blank line
            }
     }
 }
}

My personal favorite solution for this puzzle is the one by Kannan - Short, concise and gets the Job done!

Leaders board to be update with the next post!