Thread: JAVA MAGIC SQUARE

Almost nobody is going to want to open up an attachment just because you are too lazy to ask a specific question. Call us lazy, but why would you want to make it harder for somebody to help you?

Good point. Sorry about that. Here are the directions Magic Square:
a. Write a method createArithmeticSeq that prompts the user to input two numbers, first and diff. The method then creates a one-dimensional array of 16 elements ordered in an arithmetic sequence. It also outputs the arithmetic sequence. For example, if first=21 and diff =5, the arithmetic sequence is: 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96.

b. Write a method matricize that takes a one-dimensional array of 16 elements and a two-dimensional array of 4 rows, and 4 columns as parameters. This method puts the elements of the one-dimensional array into the two-dimensional array. For example, if A is the one dimensional array created in part A, and B is a two dimensional arrray, then after putting the elements of A into B, the array B is:
21 26 31 36
41 46 51 56
61 66 71 76
81 86 91 96

Part a is working fine, i just need help with part b. Thanks again!

Originally Posted by hiimjoey11

Good point. Sorry about that. Here are the directions Magic Square:
a. Write a method createArithmeticSeq that prompts the user to input two numbers, first and diff. The method then creates a one-dimensional array of 16 elements ordered in an arithmetic sequence. It also outputs the arithmetic sequence. For example, if first=21 and diff =5, the arithmetic sequence is: 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96.

b. Write a method matricize that takes a one-dimensional array of 16 elements and a two-dimensional array of 4 rows, and 4 columns as parameters. This method puts the elements of the one-dimensional array into the two-dimensional array. For example, if A is the one dimensional array created in part A, and B is a two dimensional arrray, then after putting the elements of A into B, the array B is:
21 26 31 36
41 46 51 56
61 66 71 76
81 86 91 96

Part a is working fine, i just need help with part b. Thanks again!

Have you tried anything? Part b can be accomplished with 2 for loops, and one statement inside the loops. It is very simple.

Yeah in my code as posted above i tried this :

public static String matricize(int arrayB[], int arrayC[][]) {
for(int i=0;i<4;i++) {
for(int j=0;j<4;j++) {
arrayC[i][j]=arrayB[i*4+j];
arrayB=new int[16];
arrayC=new int[4][4];
}

}
return "";
}}


the problem is, i can't get it to print out in my main..

that is almost right... I would take out the last 2 lines that are creating new int arrays, since they are overwriting what was passed in (as a general rule, parameters of methods should not be assigned in the method).

Also, the return type of the method should be void.

To print it the code is almost the same. You use the same two for loops. Instead of assigning the value at [i][j], you print the value at [i][j]. After the inner loop, print a new line.

Ah worked perfect thanks. Now part c says: Write a method reverseDiagonal that revers both diagonals of a two-dimensional array. For example, if the two-dimensional array is as show in part (b), after reversing the diagonals, the two dimensional array is:
96 26 31 81
41 71 66 56
61 51 46 76
36 86 91 21

I'm not really sure how to go about doing this. Maybe using a loop to pick out each number? sorry I am kind of new to java and our teacher kind of threw this at us.

I think i am on the right track. But it isn't working right. this is what i have so far:

    public static int [][] reverseDiagonal(int arrayReverse[][]) {
      int s=0;
      int temp;
 
      for (int row = 0; row < 4/2; row++){
        temp=arrayReverse[row][row];
        arrayReverse[row][row]=arrayReverse[4-1-row][4-1-row];
        arrayReverse[4-1-row][4-1-row]=temp;
        System.out.println(temp);
        }
}

Originally Posted by hiimjoey11

I think i am on the right track. But it isn't working right.

What isn't working about it? What do you expect it to do? What does it do instead? Try stepping through it with a debugger and checking what each line does against what you think each line should do. Where's your SSCCE?

    public static int [][] reverseDiagonal(int arrayReverse[][]) {
      int s=0;
      int temp,temp1;
 
      for (int row = 0; row < 4/2; row++){
        temp=arrayReverse[row][row];
        arrayReverse[row][row]=arrayReverse[4-1-row][4-1-row];
        arrayReverse[4-1-row][4-1-row]=temp;
        System.out.println(arrayReverse[row][row]); }
      for(int row=0;row<4/2;row++) {
        temp1=arrayReverse[row][4-1-row];
        arrayReverse[row][4-1-row]=arrayReverse[4-1-row][row];
        arrayReverse[4-1-row][row]=temp1;
        System.out.println(arrayReverse[row][row]+" ");
      }

I am trying to reverse the diagonals of the two dimensional array...but for some reason it only switches two numbers and prints them out. It doesn't go the entire way, or replace them.