Thread: [HELP] I'm creating a code to check whether 2D array is Magic Square or not

Originally Posted by Norm

What happens when the code is executed?
Why are the initial values of the boolean variables all set to true?

It seems like the code does a lot of useless work. If all the summed values must be the same, then save the first value and compare each one in turn against that value. As soon as there is a mismatch, you have the answer.

Look at a way to put the 8 sets of indexes into an array that can be used in a loop.

Please edit your post and wrap your code with code tags:

[code]
**YOUR CODE GOES HERE**
[/code]

to get highlighting and preserve formatting.

I just fixed the post!

Originally Posted by Norm

Ok, did you read my comments?
Answer this question: Why are the values of all the boolean variables initially set to true?


Where are any of those boolean variables ever set to false?

I had to initialize the boolean variables. That's why I set them to true. Now I set them all to false and it prints it's not a magic square...

No, because the array I tested the code on is a magic square. I initialized the booleans = false, and it prints it's not a magic square though. If I initialize them = true, then it prints it's magic square. So it's definitely not working...

Originally Posted by Norm

Ok, which variable(s) have the wrong values? Look at the contents of all the variables to see which one(s) are wrong.
One way to see a variable's value is to print it out.

Note: If none of the boolean variables are ever set to false, then the results will always be true.

Note: These statements can be reduced

if(rows == true && columns == true && diagonals == true) {
			magic = true;
		}

to this:

 magic = (rows == true && columns == true && diagonals == true);

Nevermind man... I just figured out the problem. I changed the initial values of the booleans:

                boolean magic = false;
		boolean rows = false;
		boolean columns = true;
		boolean diagonals = true;

And somehow the algorithm is working now, I just can't explain why! Lol

Thank you so much for helping!

The issue lies in the logic of your code where you're checking the conditions for rows, columns, and diagonals inside nested loops. Let's fix it. Here's a corrected version of your `isMagicSquare` method:

```java
public static void isMagicSquare(int arr[][]) {

boolean magic = true;
boolean rows = true;
boolean columns = true;
boolean diagonals = true;

int row1 = arr[0][0] + arr[0][1] + arr[0][2];
int row2 = arr[1][0] + arr[1][1] + arr[1][2];
int row3 = arr[2][0] + arr[2][1] + arr[2][2];

int col1 = arr[0][0] + arr[1][0] + arr[2][0];
int col2 = arr[0][1] + arr[1][1] + arr[2][1];
int col3 = arr[0][2] + arr[1][2] + arr[2][2];

int diag1 = arr[0][0] + arr[1][1] + arr[2][2];
int diag2 = arr[2][0] + arr[1][1] + arr[0][2];

// Check rows
if(row1 != row2 || row2 != row3){
rows = false;
}

// Check columns
if(col1 != col2 || col2 != col3){
columns = false;
}

// Check diagonals
if(diag1 != diag2){
diagonals = false;
}

if(!rows || !columns || !diagonals) {
magic = false;
}

if(magic) {
System.out.println("The array is a Magic Square.");
} else {
System.out.println("The array is not a Magic Square.");
}
}
```

Here's what changed:
- Moved the checks for rows, columns, and diagonals outside of the nested loops.
- Corrected the calculation of `diag2` to use `[2][0]` instead of `[1][2]`.
- Changed the conditions for rows, columns, and diagonals to check for inequality (`!=`) rather than equality (`==`).
- Removed unnecessary nested loops since you're already calculating sums outside the loops.

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