Add MagicSquare (#2411)

Maths/MagicSquare.java

@@ -0,0 +1,45 @@
+import java.util.*;
+/*A magic square of order n is an arrangement of distinct n^2 integers,in a square, such that the n numbers in all
+rows, all columns, and both diagonals sum to the same constant. A magic square contains the integers from 1 to n^2.*/
+public class MagicSquare {
+
+    public static void main(String[] args) {
+
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Input a number: ");
+        int num = sc.nextInt();
+        if ((num % 2 == 0) || (num <=0 ))
+        {
+            System.out.print("Input number must be odd and >0");
+            System.exit(0);
+        }
+
+        int[][] magic_square = new int[num][num];
+
+        int row_num = num/2;
+        int col_num = num-1;
+        magic_square[row_num][col_num] = 1;
+
+        for (int i = 2; i <= num*num; i++) {
+            if (magic_square[(row_num - 1+num) % num][(col_num + 1) % num] == 0) {
+                row_num = (row_num - 1+num) % num;
+                col_num = (col_num + 1) % num;
+            }
+            else {
+                col_num = (col_num - 1 +num) % num;
+            }
+            magic_square[row_num][col_num] = i;
+        }
+
+        // print the square
+        for (int i = 0; i < num; i++) {
+            for (int j = 0; j < num; j++) {
+                if (magic_square[i][j] < 10)  System.out.print(" ");
+                if (magic_square[i][j] < 100) System.out.print(" ");
+                System.out.print(magic_square[i][j] + " ");
+            }
+            System.out.println();
+        }
+
+    }
+}