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Re: Pascal's Triangle

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WJ wrote:

> Print the first 16 rows of Pascal's Triangle.
> 
> Gauche Scheme:
> 
> (let1 row '(1)
>   (dotimes (16)
>     (print ((#/.(.*)./ (x->string row)) 1))
>     (set! row (map + (cons 0 row) `(,@row 0)))))
> 
> 1
> 1 1
> 1 2 1
> 1 3 3 1
> 1 4 6 4 1
> 1 5 10 10 5 1
> 1 6 15 20 15 6 1
> 1 7 21 35 35 21 7 1
> 1 8 28 56 70 56 28 8 1
> 1 9 36 84 126 126 84 36 9 1
> 1 10 45 120 210 252 210 120 45 10 1
> 1 11 55 165 330 462 462 330 165 55 11 1
> 1 12 66 220 495 792 924 792 495 220 66 12 1
> 1 13 78 286 715 1287 1716 1716 1287 715 286 78 13 1
> 1 14 91 364 1001 2002 3003 3432 3003 2002 1001 364 91 14 1
> 1 15 105 455 1365 3003 5005 6435 6435 5005 3003 1365 455 105 15 1

Ocaml:

let center width string =
  let left = (width - (String.length string)) / 2 in
  let right = width - left - (String.length string) in
  String.make left ' ' ^ string ^ String.make right ' ';;

let print_row list =
  list |> List.map (fun n -> center 4 (string_of_int n))
  |> String.concat " " |>
  center 79 |> print_endline ;;

let triangle n =
  let rec newrow = function
      m::n::ns -> m+n :: newrow (n::ns)
    | xs -> xs
  and go row = function
      0 -> ()
    | n -> print_row row; go (newrow (0::row)) (n-1)
  in go [1] n ;;

triangle 16;;
                                      1
                                    1    1
                                 1    2    1
                               1    3    3    1
                            1    4    6    4    1
                          1    5    10   10   5    1
                       1    6    15   20   15   6    1
                     1    7    21   35   35   21   7    1
                  1    8    28   56   70   56   28   8    1
                1    9    36   84  126  126   84   36   9    1
             1    10   45  120  210  252  210  120   45   10   1
           1    11   55  165  330  462  462  330  165   55   11   1
        1    12   66  220  495  792  924  792  495  220   66   12   1
      1    13   78  286  715  1287 1716 1716 1287 715  286   78   13   1
   1    14   91  364  1001 2002 3003 3432 3003 2002 1001 364   91   14   1
 1    15  105  455  1365 3003 5005 6435 6435 5005 3003 1365 455  105   15   1

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Re: Pascal's Triangle "WJ" <w_a_x_man@yahoo.com> - 2015-11-28 19:03 +0000

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