Doubly-Even Magic Squares Solution
Your program should have been capable of creating the 8x8 magic square below:
1 2 62 61 60 59 7 8
9 10 54 53 52 51 15 16
48 47 19 20 21 22 42 41
40 39 27 28 29 30 34 33
32 31 35 36 37 38 26 25
24 23 43 44 45 46 18 17
49 50 14 13 12 11 55 56
57 58 6 5 4 3 63 64
Here's my version of the program:
import java.util.Scanner;
public class MagicSquare {
private static int[][] magicSquare;
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
boolean isAcceptableNumber = false;
int size = -1;
while (isAcceptableNumber == false)
{
System.out.println("Enter in size of square: ");
String sizeText = input.nextLine();
size = Integer.parseInt(sizeText);
if ((size % 2 == 0) && (size % 4 !=0))
{
System.out.println("The size must be an odd number or an even number divisible by 4");
isAcceptableNumber = false;
}
else
{
isAcceptableNumber = true;
}
}
if (size % 4 == 0)
{
createDoublyEvenSquare(size);
}
else
{
createOddSquare(size);
}
displaySquare();
}
private static void createOddSquare(int size)
{
magicSquare = new int[size][size];
int row = 0;
int column = size/2;
int lastRow = row;
int lastColumn = column;
magicSquare[row][column]= 1;
int matrixSize = size*size;
for (int k=2;k < matrixSize+1;k++)
{
//check if we need to wrap to
//opposite row
if (row - 1 < 0)
{
row = size-1;
}
else
{
row--;
}
//check if we need to wrap
//to opposite column
if (column + 1 == size)
{
column = 0;
}
else
{
column++;
}
if (magicSquare[row][column] == 0)
{
magicSquare[row][column] = k;
}
else
{
row = lastRow;
column = lastColumn;
if (row + 1 == size)
{
row=0;
}
else
{
row++;
}
magicSquare[row][column] = k;
}
lastRow = row;
lastColumn= column;
}
}
private static void createDoublyEvenSquare(int size)
{
magicSquare = new int[size][size];
int countUpNumber = 1;
StringBuilder usedNumbers = new StringBuilder();
int miniSquareNumber = size/4;
for (int j=0;j < magicSquare.length;j++)
{
//populate the corner mini-squares
if ((j < miniSquareNumber) || (j > magicSquare.length-1-miniSquareNumber))
{
for (int k=0;k < miniSquareNumber;k++)
{
magicSquare[j][k] = countUpNumber;
usedNumbers.append("/"+countUpNumber+"/");
countUpNumber++;
}
countUpNumber = countUpNumber+(miniSquareNumber+miniSquareNumber);
for (int k=magicSquare.length-miniSquareNumber;k < magicSquare.length;k++)
{
magicSquare[j][k] = countUpNumber;
usedNumbers.append("/"+countUpNumber+"/");
countUpNumber++;
}
}
else //populate the large center square
{
countUpNumber = countUpNumber+miniSquareNumber;
for (int k=miniSquareNumber;k < magicSquare.length-miniSquareNumber;k++)
{
magicSquare[j][k] = countUpNumber;
usedNumbers.append("/"+countUpNumber+"/");
countUpNumber++;
}
countUpNumber = countUpNumber+miniSquareNumber;
}
}
int countDownNumber = size*size - miniSquareNumber;
//populate remaining squares
for (int l=0;l < magicSquare.length);l++)
{
for (int m=0;m < magicSquare[l].length);m++)
{
if (magicSquare[l][m] == 0)
{
while (usedNumbers.indexOf("/"+countDownNumber+"/") != -1)
{
countDownNumber--;
}
magicSquare[l][m] = countDownNumber;
countDownNumber--;
}
}
}
}
private static void displaySquare()
{
int magicConstant = 0;
for (int j=0;j < magicSquare.length;j++)
{
for (int k=0;k < magicSquare[j].length);k++)
{
System.out.print(magicSquare[j][k] + " ");
}
System.out.print("\n");
magicConstant = magicConstant + magicSquare[j][0];
}
System.out.print("The magic constant is " + magicConstant);
}
} 
