Magic Square | Even Order

Difficulty Level :
Hard
A magic square of order n is an arrangement of n^2 numbers, usually distinct 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.The constant sum in every row, column and diagonal is called the magic constant or magic sum, M. The magic constant of a normal magic square depends only on n and has the following value: M = n (n^2 + 1) / 2.Examples:  
Magic Square of order 3:
-----------------------
 2   7   6
 9   5   1
 4   3   8

Magic Square of order 4:
-----------------------
16 2 3 13 
5 11 10 8 
9  7 6 12 
4 14 15 1 

Magic Square of order 8:
-----------------------
64 63  3  4  5  6 58 57 
56 55 11 12 13 14 50 49 
17 18 46 45 44 43 23 24 
25 26 38 37 36 35 31 32 
33 34 30 29 28 27 39 40 
41 42 22 21 20 19 47 48 
16 15 51 52 53 54 10 9 
8  7  59 60 61 62 2  1 
A bit of Theory: Magic squares are divided into three major categories depending upon order of square. 1) Odd order Magic Square. Example: 3,5,7,... (2*n +1) 2) Doubly-even order Magic Square. Example : 4,8,12,16,.. (4*n) 3) Singly-even order Magic Square. Example : 6,10,14,18,..(4*n +2) 
Algorithm for Doubly-even Magic Square :  
    define an 2-D array of order n*n
    // fill array with their index-counting 
    // starting from 1
    for ( i = 0; i<n; i++)
    {
        for ( j = 0; j<n; j++)
            // filling array with its count value 
            // starting from 1;
            arr[i][j] = (n*i) + j + 1;        
    }

    // change value of Array elements 
    // at fix location as per rule 
    // (n*n+1)-arr[i][j]
    // Top Left corner of Matrix 
   // (order (n/4)*(n/4))
    for ( i = 0; i<n/4; i++)
    {
        for ( j = 0; j<n/4; j++)
            arr[i][j] = (n*n + 1) - arr[i][j];
    }

    // Top Right corner of Matrix 
    // (order (n/4)*(n/4))
    for ( i = 0; i< n/4; i++)
    {
        for ( j = 3* (n/4); j<n; j++)
            arr[i][j] = (n*n + 1) - arr[i][j];
    }

    // Bottom Left corner of Matrix 
    // (order (n/4)*(n/4))
    for ( i = 3* n/4; i<n; i++)
    {
        for ( j = 0; j<n/4; j++)
            arr[i][j] = (n*n + 1) - arr[i][j];
    }
 
    // Bottom Right corner of Matrix 
   // (order (n/4)*(n/4))
    for ( i = 3* n/4; i<n; i++)
    {
        for ( j = 3* n/4; j<n; j++)
            arr[i][j] = (n*n + 1) - arr[i][j];
    }
 
    // Centre of Matrix (order (n/2)*(n/2))
    for ( i = n/4; i<3* n/4; i++)
    {
        for ( j = n/4; j<3* n/4; j++)
            arr[i][j] = (n*n + 1) - arr[i][j];
    } 
 
Explanation with an example:(order 4)1) Define array of order 4*4 and fill it with its count value as:  
2) Change value of top-left corner matrix of order (1*1):  
3) Change value of top-right corner matrix of order (1*1):  
4) Change value of bottom-left corner matrix of order (1*1):  
5) Change value of bottom-right corner matrix of order (1*1):  
6) Change value of centre matrix of order (2*2):  
Implementation for Doubly-even Magic Square:   
C++
Java
Python3
C#
PHP
Javascript
// C++ Program to print Magic square// of Doubly even order#include<iostream>using namespace std; // Function for calculating Magic squarevoid doublyEven( int n ){    int arr[n][n], i, j;     // filling matrix with its count value    // starting from 1;    for ( i = 0; i < n; i++)        for ( j = 0; j < n; j++)            arr[i][j] = (n*i) + j + 1;         // change value of Array elements    // at fix location as per rule    // (n*n+1)-arr[i][j]    // Top Left corner of Matrix    // (order (n/4)*(n/4))    for ( i = 0; i < n/4; i++)        for ( j = 0; j < n/4; j++)            arr[i][j] = (n*n + 1) - arr[i][j];         // Top Right corner of Matrix    // (order (n/4)*(n/4))    for ( i = 0; i < n/4; i++)        for ( j = 3 * (n/4); j < n; j++)            arr[i][j] = (n*n + 1) - arr[i][j];         // Bottom Left corner of Matrix    // (order (n/4)*(n/4))    for ( i = 3 * n/4; i < n; i++)        for ( j = 0; j < n/4; j++)            arr[i][j] = (n*n+1) - arr[i][j];         // Bottom Right corner of Matrix    // (order (n/4)*(n/4))    for ( i = 3 * n/4; i < n; i++)        for ( j = 3 * n/4; j < n; j++)            arr[i][j] = (n*n + 1) - arr[i][j];         // Centre of Matrix (order (n/2)*(n/2))    for ( i = n/4; i < 3 * n/4; i++)        for ( j = n/4; j < 3 * n/4; j++)            arr[i][j] = (n*n + 1) - arr[i][j];     // Printing the magic-square    for (i = 0; i < n; i++)    {        for ( j = 0; j < n; j++)            cout << arr[i][j] << " ";        cout << "\n";    }} // driver programint main(){    int n=8;    doublyEven(n); //Function call    return 0;}
// Java program to print Magic square// of Doubly even orderimport java.io.*; class GFG{    // Function for calculating Magic square    static void doublyEven(int n)    {        int[][] arr = new int[n][n];        int i, j;          // filling matrix with its count value        // starting from 1;        for ( i = 0; i < n; i++)            for ( j = 0; j < n; j++)                arr[i][j] = (n*i) + j + 1;               // change value of Array elements        // at fix location as per rule        // (n*n+1)-arr[i][j]        // Top Left corner of Matrix        // (order (n/4)*(n/4))        for ( i = 0; i < n/4; i++)            for ( j = 0; j < n/4; j++)                arr[i][j] = (n*n + 1) - arr[i][j];             // Top Right corner of Matrix        // (order (n/4)*(n/4))        for ( i = 0; i < n/4; i++)            for ( j = 3 * (n/4); j < n; j++)                arr[i][j] = (n*n + 1) - arr[i][j];              // Bottom Left corner of Matrix        // (order (n/4)*(n/4))        for ( i = 3 * n/4; i < n; i++)            for ( j = 0; j < n/4; j++)                arr[i][j] = (n*n+1) - arr[i][j];             // Bottom Right corner of Matrix        // (order (n/4)*(n/4))        for ( i = 3 * n/4; i < n; i++)            for ( j = 3 * n/4; j < n; j++)                arr[i][j] = (n*n + 1) - arr[i][j];            // Centre of Matrix (order (n/2)*(n/2))        for ( i = n/4; i < 3 * n/4; i++)            for ( j = n/4; j < 3 * n/4; j++)                arr[i][j] = (n*n + 1) - arr[i][j];          // Printing the magic-square        for (i = 0; i < n; i++)        {            for ( j = 0; j < n; j++)                System.out.print(arr[i][j]+" ");            System.out.println();        }    }         // driver program    public static void main (String[] args)    {        int n = 8;        // Function call        doublyEven(n);    }} // Contributed by Pramod Kumar
# Python program to print magic square of double order def DoublyEven(n):         # 2-D matrix with all entries as 0    arr = [[(n*y)+x+1 for x in range(n)]for y in range(n)]     # Change value of array elements at fix location    # as per the rule (n*n+1)-arr[i][[j]         # Corners of order (n/4)*(n/4)    # Top left corner    for i in range(0,n//4):        for j in range(0,n//4):            arr[i][j] = (n*n + 1) - arr[i][j];         # Top right corner    for i in range(0,n//4):        for j in range(3 * (n//4),n):            arr[i][j] = (n*n + 1) - arr[i][j];     # Bottom Left corner    for i in range(3 * (n//4),n):        for j in range(0,n//4):            arr[i][j] = (n*n + 1) - arr[i][j];         # Bottom Right corner    for i in range(3 * (n//4),n):        for j in range(3 * (n//4),n):            arr[i][j] = (n*n + 1) - arr[i][j];                 # Centre of matrix,order (n/2)*(n/2)    for i in range(n//4,3 * (n//4)):        for j in range(n//4,3 * (n//4)):            arr[i][j] = (n*n + 1) - arr[i][j];         # Printing the square    for i in range(n):        for j in range(n):            print ('%2d ' %(arr[i][j]),end=" ")        print()         # Driver Programn = 8DoublyEven(n) # Contributed by Harshit Agrawal           
// C# program to print Magic square// of Doubly even orderusing System; class GFG{// Function for calculating Magic squarepublic static void doublyEven(int n){     int[,] arr = new int[n,n];    int i, j;     // filling matrix with its count    // value starting from 1;    for (i = 0; i < n; i++)    {        for (j = 0; j < n; j++)        {            arr[i, j] = (n * i) + j + 1;        }    }     // change value of Array elements    // at fix location as per rule    // (n*n+1)-arr[i][j]    // Top Left corner of Matrix    // (order (n/4)*(n/4))    for (i = 0; i < n / 4; i++)    {        for (j = 0; j < n / 4; j++)        {            arr[i, j] = (n * n + 1) - arr[i, j];        }    }     // Top Right corner of Matrix    // (order (n/4)*(n/4))    for (i = 0; i < n / 4; i++)    {        for (j = 3 * (n / 4); j < n; j++)        {            arr[i, j] = (n * n + 1) - arr[i, j];        }    }     // Bottom Left corner of Matrix    // (order (n/4)*(n/4))    for (i = 3 * n / 4; i < n; i++)    {        for (j = 0; j < n / 4; j++)        {            arr[i, j] = (n * n + 1) - arr[i, j];        }    }     // Bottom Right corner of Matrix    // (order (n/4)*(n/4))    for (i = 3 * n / 4; i < n; i++)    {        for (j = 3 * n / 4; j < n; j++)        {            arr[i, j] = (n * n + 1) - arr[i, j];        }    }     // Centre of Matrix (order (n/2)*(n/2))    for (i = n / 4; i < 3 * n / 4; i++)    {        for (j = n / 4; j < 3 * n / 4; j++)        {            arr[i, j] = (n * n + 1) - arr[i, j];        }    }     // Printing the magic-square    for (i = 0; i < n; i++)    {        for (j = 0; j < n; j++)        {            Console.Write(arr[i, j] + " " + " ");        }        Console.WriteLine();    }} // Driver Codepublic static void Main(string[] args){    int n = 8;         // Function call    doublyEven(n);}} // This code is contributed by Shrikant13
<?php// PHP Program to print Magic square// of Doubly even order // Function for calculating Magic squarefunction doublyEven($n){    $arr = array_fill(0, $n,           array_fill(0, $n, 0));     // filling matrix with its count    // value starting from 1;    for ( $i = 0; $i < $n; $i++)        for ( $j = 0; $j < $n; $j++)            $arr[$i][$j] = ($n * $i) + $j + 1;         // change value of Array elements at fix    // location as per rule (n*n+1)-arr[i][j]    // Top Left corner of Matrix    // (order (n/4)*(n/4))    for ($i = 0; $i < $n / 4; $i++)        for ($j = 0; $j < $n / 4; $j++)            $arr[$i][$j] = ($n * $n + 1) -                            $arr[$i][$j];         // Top Right corner of Matrix    // (order (n/4)*(n/4))    for ($i = 0; $i < $n / 4; $i++)        for ($j = 3 * ($n / 4); $j < $n; $j++)            $arr[$i][$j] = ($n * $n + 1) -                            $arr[$i][$j];         // Bottom Left corner of Matrix    // (order (n/4)*(n/4))    for ($i = 3 * $n / 4; $i < $n; $i++)        for ($j = 0; $j < $n / 4; $j++)            $arr[$i][$j] = ($n * $n + 1) -                            $arr[$i][$j];         // Bottom Right corner of Matrix    // (order (n/4)*(n/4))    for ($i = 3 * $n / 4; $i < $n; $i++)        for ($j = 3 * $n / 4; $j < $n; $j++)            $arr[$i][$j] = ($n * $n + 1) -                            $arr[$i][$j];     // Centre of Matrix (order (n/2)*(n/2))    for ($i = $n / 4; $i < 3 * $n / 4; $i++)        for ($j = $n / 4; $j < 3 * $n / 4; $j++)            $arr[$i][$j] = ($n * $n + 1) -                            $arr[$i][$j];     // Printing the magic-square    for ($i = 0; $i < $n; $i++)    {        for ($j = 0; $j < $n; $j++)            echo $arr[$i][$j] . " ";        echo "\n";    }} // Driver Code$n = 8;doublyEven($n); //Function call // This code is contributed by mits?>
<script> // javascript program to print Magic square// of Doubly even order // Function for calculating Magic square    function doublyEven(n)    {        var arr = Array(n).fill(0).map(x => Array(n).fill(0));        var i, j;          // filling matrix with its count value    // starting from 1;    for ( i = 0; i < n; i++)        for ( j = 0; j < n; j++)            arr[i][j] = (n*i) + j + 1;       // change value of Array elements    // at fix location as per rule    // (n*n+1)-arr[i][j]    // Top Left corner of Matrix    // (order (parseInt(n/4))*(parseInt(n/4)))    for ( i = 0; i < parseInt(n/4); i++)        for ( j = 0; j < parseInt(n/4); j++)            arr[i][j] = (n*n + 1) - arr[i][j];     // Top Right corner of Matrix    // (order (parseInt(n/4))*(parseInt(n/4)))    for ( i = 0; i < parseInt(n/4); i++)        for ( j = 3 * (parseInt(n/4)); j < n; j++)            arr[i][j] = (n*n + 1) - arr[i][j];      // Bottom Left corner of Matrix    // (order (parseInt(n/4))*(parseInt(n/4)))    for ( i = 3 * parseInt(n/4); i < n; i++)        for ( j = 0; j < parseInt(n/4); j++)            arr[i][j] = (n*n+1) - arr[i][j];     // Bottom Right corner of Matrix    // (order (parseInt(n/4))*(parseInt(n/4)))        for ( i = 3 * parseInt(n/4); i < n; i++)            for ( j = 3 * parseInt(n/4); j < n; j++)                arr[i][j] = (n*n + 1) - arr[i][j];            // Centre of Matrix (order (n/2)*(n/2))        for ( i = parseInt(n/4); i < 3 * parseInt(n/4); i++)            for ( j = parseInt(n/4); j < 3 * parseInt(n/4); j++)                arr[i][j] = (n*n + 1) - arr[i][j];          // Printing the magic-square    for (i = 0; i < n; i++)    {        for ( j = 0; j < n; j++)            document.write(arr[i][j]+"  ");        document.write('<br>');    }} // driver programvar n = 8;// Function calldoublyEven(n); // This code is contributed by Amit Katiyar</script>
Output:  
64   63   3    4    5    6    58   57   
56   55   11   12   13   14   50   49   
17   18   46   45   44   43   23   24   
25   26   38   37   36   35   31   32   
33   34   30   29   28   27   39   40   
41   42   22   21   20   19   47   48   
16   15   51   52   53   54   10   9   
8    7    59   60   61   62   2   1 
Time complexity : O(n2)Auxiliary Space: O(n2)
Reference: http://www.1728.org/magicsq2.htmlThis article is contributed by Shivam Pradhan (anuj_charm). If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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