/* NetRexx */
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zigzag(5)

return

method zigzag(msize) public static

  row = 1
  col = 1

  ziggy = Rexx(0)
  loop j_ = 0 for msize * msize
    ziggy[row, col] = j_
    if (row + col) // 2 == 0 then do
      if col < msize then -
        col = col + 1
      else row = row + 2
      if row \== 1 then -
        row = row - 1
      end
    else do
      if row < msize then -
        row = row + 1
      else col = col + 2
      if col \== 1 then -
        col = col - 1
      end
    end j_

  L = (msize * msize - 1).length             /*for a constant element width.  */
  loop row = 1 for msize                     /*show all the matrix's rows.    */
    rowOut = ''
    loop col = 1 for msize
      rowOut = rowOut ziggy[row, col].right(L)
      end col
    say rowOut
    end row

  return