MagicSquares.nim0

## Print a magic square for odd values of size of the square.
## https://en.wikipedia.org/wiki/Magic_square
##
## Compile with `$ ./nim0 comp examples/MagicSquares`
## Try it with `$ ./nim0 run examples/MagicSquares MagicSquare 3`
## or `$ ./nim0 run examples/MagicSquares MagicSquare 11`

proc MagicSquare* =
  var
    i, j, x, nx, nsq, n: int
    M: array[13, array[13, int]]
  
  # Remember, Nim0 does not have functions!
  readInt(n)

  nsq = n * n
  x = 0
  i = n div 2
  j = n
  while x < nsq:
    nx = n + x
    j = (j - 1) mod n
    if j < 0:
      j = j + n
    x = x + 1
    M[i][j] = x
    while x < nx:
      i = (i + 1) mod n
      j = (j + 1) mod n
      x = x + 1
      M[i][j] = x

  # Write result
  i = 0
  while i < n:
    j = 0
    while j < n:
      write(M[i][j])
      write(' ')
      j = j + 1
    i = i + 1
    writeLine