#!/usr/bin/perl -w
use feature qw(say);
use Memoize;
use Benchmark;

=results:
Benchmark: timing 100000 iterations of JavaFan, Marshall, 
                                      Memoize, Recurse...
   JavaFan:  2 wallclock secs ( 2.00 usr +  0.00 sys =  2.00 CPU) 
               @ 49975.01/s (n=100000)
  Marshall:  6 wallclock secs ( 6.59 usr +  0.00 sys =  6.59 CPU) 
               @ 15165.30/s (n=100000)
   Memoize: 50 wallclock secs (49.45 usr +  0.25 sys = 49.70 CPU) 
               @ 2011.99/s (n=100000)
   Recurse: 644 wallclock secs (641.27 usr +  0.05 sys = 641.31 CPU) 
              @ 155.93/s (n=100000)
=cut              

timethese (100000,

 { JavaFan=> 
    q{
       sub fib  {
                   my $PHI = (1 + sqrt(5)) / 2;
                   int($PHI ** $_[0] / sqrt(5) + 0.5)
                 }
       foreach (0 .. 15)
       {
         # print fib($_), "\n";
          fib($_);
       }
     },
          
   Marshall =>
    q{
        foreach (1..15)
        {
           # print fibonacci($_), " ";
            fibonacci($_);
         }

         sub fibonacci
         {
             my $number = shift;
  
             my $cur_num   = 1;
             my $prev_num  = 1;
             my $sum;
         
             return 1  if ($number == 1 || $number == 2);
       
             $number -= 2;
     
             while ($number--)
             {
                $sum = $cur_num + $prev_num;
                $prev_num = $cur_num;
                $cur_num  = $sum;
             }     
             return $sum;
         }
     },
   
   Recurse =>
      q{
          foreach (1..15)
          {
            # print fibx($_), "\n";
              fibx($_);
          }
       
         # Compute Fibonacci numbers
           sub fibx 
           {
             my $n = shift;
             return $n if $n < 2;
             fibx($n-1) + fibx($n-2);
           }
      },
      
   Memoize =>
      q{
          memoize('fiby');
          foreach (1..15)
          {
             fiby($_);
            #print fiby($_);
             
          }
       
         # Compute Fibonacci numbers
           sub fiby 
           {
             my $n = shift;
             return $n if $n < 2;
             fiby($n-1) + fiby($n-2);
           }
      },        
 } 
);