Perl Weekly Challenge 003

ch-1.pl

use strict;
use warnings;
##
# Create a script to generate 5-smooth numbers, whose prime divisors are less or equal to 5. 
# They are also called Hamming/Regular/Ugly numbers.  
##
use boolean; 

sub is_divisible{
    my($divisor) = @_;  
    return sub{
        my($x) = @_;
        if($x % $divisor == 0){
            return true;  
        }   
        return false;  
    }   
}  

my $is_divisible_by_2 = is_divisible(2);  
my $is_divisible_by_3 = is_divisible(3);  
my $is_divisible_by_5 = is_divisible(5);  

sub is_hamming{
    my($x) = @_;
    if($x == 1){
        return true;  
    }  
    if($is_divisible_by_2->($x)){
        return is_hamming($x/2);  
    }    
    if($is_divisible_by_3->($x)){
        return is_hamming($x/3);  
    }    
    if($is_divisible_by_5->($x)){
        return is_hamming($x/5);  
    }    
    return false;  
}  

sub generate_hamming_sequence{  
        my($x) = @_;  
	if($x == 1){
            return true;  
        }  
	generate_hamming_sequence($x - 1);  
	if(is_hamming($x)){
            print("$x ");  
        }  
} 

generate_hamming_sequence(64);   

ch-2.pl

use strict;
use warnings;
##
# Create a script that generates Pascal Triangle. 
# Accept number of rows from the command line. 
# The Pascal Triangle should have at least 3 rows.
## 

##
# How to compute Pascal's Triangle. 
# After the inital row(s) with 1 entries, the entry for the n-th row and k-th column is defined as
#                             (n-1)!             (n-1)!                             
#                       -------------------- + ------------
#                       (k-1)!((n-1)-(k-1))!   k!((n-1)-k)!  
##

sub compute_entry{
    my($row, $column) = @_;
    unless($row < 2){
        my($x0, $y0, $x1, $y1);  
        $x0 = factorial($row - 1);  
        $y0 = factorial($column - 1) * factorial(($row - 1) - ($column - 1));             
        $x1 = factorial($row - 1);  
        $y1 = factorial($column) * factorial(($row - 1) - $column); 
        return int($x0 / $y0) + int($x1 / $y1);   
    } 
    return 1;   
} 

sub factorial{
    my($n) = @_;
    unless($n < 1){
        return $n * factorial($n - 1); 
    }
    return 1;  
}

##
# Main    
##  
my $max = $ARGV[0];  
my $padding = " ";
my $padding_length = $max;  
for my $i (1 .. $max){
    $padding_length = $padding_length - 1;  
    print $padding x $padding_length;  
    for my $j (1 .. $i){
        print compute_entry($i - 1, $j - 1) . " ";  
    } 
    print "\n";       
}