added ch2 with extra

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diff --git a/challenge-054/cristian-heredia/perl/ch-2.pl b/challenge-054/cristian-heredia/perl/ch-2.pl
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+use strict;
+use warnings;
+no warnings 'recursion';
+use Data::Dumper;
+
+#Collatz Conjecture
+#Contributed by Ryan Thompson
+#It is thought that the following sequence will always reach 1:
+#
+#$n = $n / 2 when $n is even
+#$n = 3*$n + 1 when $n is odd
+#For example, if we start at 23, we get the following sequence:
+#
+#23 → 70 → 35 → 106 → 53 → 160 → 80 → 40 → 20 → 10 → 5 → 16 → 8 → 4 → 2 → 1
+#
+#Write a function that finds the Collatz sequence for any positive integer. Notice how the sequence itself may go far above the original starting number.
+
+#Extra Credit
+#Have your script calculate the sequence length for all starting numbers up to 1000000 (1e6), and output the starting number and sequence length for the longest 20 sequences.
+
+
+###Variables
+my $number;
+my $result = '';
+my $origin;
+my $minimum = '2';
+my $maximum = '1000000';
+my $option;
+my %sizes;
+my @array;
+my $length;
+my $numberToShow = 20;
+
+selectOption();
+
+sub selectOption {
+	
+	print "Please, select the option (1 or 2) that you prefer\n 1 Introduce a number\n 2 From $minimum to $maximum, output the starting number and sequence length for the longest $numberToShow sequences\n";
+	$option = <>;
+	$option =~ s/^\s+|\s+$//g;
+	if ($option =~ /^-?\d+$/ and $option == 1) {
+		requestNumber();
+	}
+	elsif ($option =~ /^-?\d+$/ and $option == 2) {
+		extraCredit();
+	}
+	else {
+		selectOption();
+	}
+}
+
+sub requestNumber {
+
+	print "Please enter the number for which you want to know its Collatz sequence\n";
+	$number = <>;
+	$number =~ s/^\s+|\s+$//g;
+	$origin = $number;
+	if ($number =~ /^-?\d+$/ and $number >= 1) {
+		$result = "$number";
+		findCollatz();
+	} 
+	else {
+		requestNumber();
+	}
+}
+
+sub findCollatz {
+	
+	if ($number == 1) {
+		if ($option == 1){
+			print "The Collatz sequence for $origin is:\n$result\n";
+		}
+		else {
+			countResult();
+		}	
+	}
+	elsif ($number % 2 == 0) {
+		$number = $number / 2;
+		$result = $result." - $number";
+		findCollatz();
+	}
+	else {
+		$number = 3*$number + 1;
+		$result = $result." - $number";
+		findCollatz();
+	}
+}
+
+sub extraCredit {
+
+	$sizes{1} = 1;
+	foreach (my $i = $minimum; $i <= $maximum; $i++) {
+		$result = '';
+		$number = $i;
+		findCollatz();
+		$sizes{$i} = $length;	
+	}
+	
+	sortHash();
+
+}
+
+sub countResult {
+	
+	@array = split(' - ', $result);
+	$length = @array;
+}
+
+
+sub sortHash {
+
+	my $count = 0;
+
+	foreach my $key (sort { $sizes{$b} <=> $sizes{$a} } keys %sizes) {
+		print "The starting number is: $key and the length is:$sizes{$key}\n";
+		$count++;
+		if ($count == $numberToShow) {
+			last;
+		}
+    }
+}
+
+