Язык Mathematica

• Вариант 1 (медленно работает)

F[n_] := F[n-1] + F[n-2];
F[0] = F[1] = 1;
F[1000]

• Вариант 2 (быстро работает)

F[n_] := (F[n] = F[n-1] + F[n-2]);
F[0] = F[1] = 1;
F[1000]

Tcl

#!/usr/local/bin/tclsh
proc fib {n} {
    if {$n < 2} {
        return 1
    } else {
       return [expr {[fib [expr {$n-2}]] + [fib [expr {$n-1}]]}]
    }
}
set N [lindex $argv 0]
if {$N < 1} { set N 1 }
puts [fib $N]

Ruby

#!/usr/local/bin/ruby
def fib(n)
    if n < 2 then
        1
    else
        fib(n-2) + fib(n-1)
    end
end

N = Integer(ARGV.shift || 1)
puts fib(N)

Язык Perl

use strict;
use integer;

sub fib {
    return $_[0] < 2 ? 1 : fib($_[0]-2) + fib($_[0]-1);
}

my $N = ($ARGV[0] < 1) ? 1 : $ARGV[0];
my $fib = fib($N);
print "$fib\n";

Язык C

#include <stdio.h>
#include <stdlib.h>
unsigned long
fib(unsigned long n) {
    if (n < 2)
    return(1);
    else
    return(fib(n-2) + fib(n-1));
}
int
main(int argc, char *argv[]) {
    int N = ((argc == 2) ? atoi(argv[1]) : 1);
    printf("%ld\n", fib(N));
    return(0);
}

Язык FreePascal

program fibo;
uses SysUtils;

function fib(N : integer) : longint;
begin
    if N < 2 then fib := 1
    else fib := fib(N-2) + fib(N-1);
End;

var
    NUM : integer;
    f : longint;

begin
    if ParamCount = 0 then
        NUM := 1
    else
        NUM := StrToInt(ParamStr(1));

    if NUM < 1 then NUM := 1;
    f := fib(NUM);
    WriteLn( IntToStr(f) );
end.

Язык Python

#!/usr/local/bin/python
import sys
def fib(n):
    if (n < 2):
        return(1)
    return( fib(n-2) + fib(n-1) )

def main():
    N = int(sys.argv[1])
    #sys.setrecursionlimit(3000)
    print fib(N)

main()

Язык Ocaml

let rec fib n =
  if n < 2 then 1
  else fib (n - 2) + fib (n - 1)

let _ =
  let n =
    try int_of_string Sys.argv.(1)
    with Invalid_argument _ -> 1 in
  Printf.printf "%d\n" (fib n)

Язык Lisp

BeautifierPlugin Error: Unable to handle "lisp" syntax.