A magic square of size N is a square with the numbers from 1 to N ** 2 arranged so that each row, column, and the two long diagonals have the same sum. For example, a magic square for N = 5 could be:
+------------------------+
| 15 | 8 | 1 | 24 | 17 |
+------------------------+
| 16 | 14 | 7 | 5 | 23 |
+------------------------+
| 22 | 20 | 13 | 6 | 4 |
+------------------------+
| 3 | 21 | 19 | 12 | 10 |
+------------------------+
| 9 | 2 | 25 | 18 | 11 |
+------------------------+
In this case the magic sum is 65. All rows, columns, and both diagonals add up to that.
- magic_square.rb - Actual code
- test_magic_square.rb - test cases for orders 3, 4, 6 and 5
To execute code:
> ruby magic_square.rb <order as integer value>
Examples:
> ruby magic_square.rb 3
> ruby magic_square.rb 4
> ruby magic_square.rb 6
To run test cases:
> ruby test_magic_square.rb
Ruby version 2.1.5 used for testing.