- Added solutions by Ulrich Rieke.

- Added solutions by Robert DiCicco.
- Added solutions by Eric Cheung.
- Added solutions by Laurent Rosenfeld.
- Added solutions by Wanderdoc.
- Added solutions by W. Luis Mochan.
- Added solutions by E. Choroba.
- Added solutions by David Ferrone.
- Added solutions by Mark Anderson.
- Added solutions by rcmlz.
- Added solutions by Peter Campbell Smith.
- Added solutions by PokGoPun.
- Added solutions by Thomas Kohler.
- Added solutions by Lubos Kolouch.
- Added solutions by Luca Ferrari.
- Added solutions by Jaldhar H. Vyas.

18 files changed, 819 insertions, 0 deletions

diff --git a/challenge-236/eric-cheung/python/ch-1.py b/challenge-236/eric-cheung/python/ch-1.py
new file mode 100755
index 0000000000..87c8692ed0
--- /dev/null
+++ b/challenge-236/eric-cheung/python/ch-1.py
@@ -0,0 +1,29 @@
+

+## arrInputBill = [5, 5, 5, 10, 20]  ## Example 1

+## arrInputBill = [5, 5, 10, 10, 20]  ## Example 2

+arrInputBill = [5, 5, 5, 20]  ## Example 3

+

+arrChange = [0, 0, 0]

+bSucceed = True

+

+for nIndx in range(len(arrInputBill)):    

+    if arrInputBill[nIndx] == 5:

+        arrChange[0] = arrChange[0] + 1

+    elif arrInputBill[nIndx] == 10:

+        if arrChange[0] < 1:

+            bSucceed = False

+            break

+        arrChange[0] = arrChange[0] - 1

+        arrChange[1] = arrChange[1] + 1

+    elif arrInputBill[nIndx] == 20:

+        if arrChange[0] < 3 and (arrChange[0] < 1 or arrChange[1] < 1):

+            bSucceed = False

+            break

+        arrChange[2] = arrChange[2] + 1

+        if arrChange[1] > 0:

+            arrChange[1] = arrChange[1] - 1

+            arrChange[0] = arrChange[0] - 1

+        else:

+            arrChange[0] = arrChange[0] - 3

+

+print (bSucceed)

diff --git a/challenge-236/eric-cheung/python/ch-2.py b/challenge-236/eric-cheung/python/ch-2.py
new file mode 100755
index 0000000000..c503507ba1
--- /dev/null
+++ b/challenge-236/eric-cheung/python/ch-2.py
@@ -0,0 +1,24 @@
+

+arrInput = [4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5,  11,  1,  12,  2,  9,  10]  ## Example 1

+## arrInput = [0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19]  ## Example 2

+## arrInput = [9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17]  ## Example 3

+

+arrIndx = [0] * len(arrInput)

+arrOutput = []

+

+for nIndxLoop in range(len(arrIndx)):

+    if arrIndx[nIndxLoop] == 1:

+        continue

+

+    arrTemp = []

+    nTempIndxLoop = nIndxLoop

+

+    while arrInput[nTempIndxLoop] not in arrTemp:

+        arrTemp.append(arrInput[nTempIndxLoop])

+        arrIndx[nTempIndxLoop] = 1

+        nTempIndxLoop = arrInput[nTempIndxLoop]

+

+    arrOutput.append(arrTemp)

+

+## print (arrOutput)

+print (len(arrOutput))

diff --git a/challenge-236/laurent-rosenfeld/blog.txt b/challenge-236/laurent-rosenfeld/blog.txt
new file mode 100644
index 0000000000..8fcccd56d0
--- /dev/null
+++ b/challenge-236/laurent-rosenfeld/blog.txt
@@ -0,0 +1 @@
+https://blogs.perl.org/users/laurent_r/2023/09/perl-weekly-challenge-236-array-loops.html
diff --git a/challenge-236/laurent-rosenfeld/perl/ch-2.pl b/challenge-236/laurent-rosenfeld/perl/ch-2.pl
new file mode 100644
index 0000000000..d0937e17a6
--- /dev/null
+++ b/challenge-236/laurent-rosenfeld/perl/ch-2.pl
@@ -0,0 +1,20 @@
+use strict;
+use warnings;
+use feature 'say';
+
+sub find_loops {
+    my @in = @_;
+    my $count = 0;
+    for my $i (0..$#in) {
+        my $j = $i;
+        # say $i;
+        while (1) {
+            last unless defined $in[$j];
+            # say "\t", $j, "\t", @in[$j];
+            ++$count and last if $in[$j] == $i;
+            $j = $in[$j];
+        }
+    }
+    return $count;
+}
+
diff --git a/challenge-236/laurent-rosenfeld/raku/ch-2.raku b/challenge-236/laurent-rosenfeld/raku/ch-2.raku
new file mode 100644
index 0000000000..0241c93c49
--- /dev/null
+++ b/challenge-236/laurent-rosenfeld/raku/ch-2.raku
@@ -0,0 +1,24 @@
+sub find-loops (@in) {
+    my $count = 0;
+    for 0..@in.end -> $i {
+        my $j = $i;
+        loop {
+            last unless @in[$j].defined;
+            # say "\t", $j, "\t", @in[$j];
+            ++$count and last if @in[$j] == $i;
+            $j = @in[$j];
+        }
+    }
+    return $count;
+}
+
+my @tests =
+    (4,6,3,8,15,0,13,18,7,16,14,19,17,5,11,1,12,2,9,10),
+    (0,1,13,7,6,8,10,11,2,14,16,4,12,9,17,5,3,18,15,19),
+    (9,8,3,11,5,7,13,19,12,4,14,10,18,2,16,1,0,15,6,17),
+    (0,1,13,7,6,8,10,11,2,14,16,4,12,9,17,5,3);
+
+for @tests -> @test {
+    say @test;
+    say "\tNumber of loops: ", find-loops @test;
+}
diff --git a/challenge-236/rcmlz/raku/ch-1.raku b/challenge-236/rcmlz/raku/ch-1.raku
new file mode 100644
index 0000000000..ca8a45ecf0
--- /dev/null
+++ b/challenge-236/rcmlz/raku/ch-1.raku
@@ -0,0 +1,48 @@
+unit module rcmlz::raku::task-one:ver<0.0.1>:auth<github:rcmlz>:api<1>;
+
+# run in terminal: raku --optimize=3 -I challenge-nr236/rcmlz/raku/ -- test/challenge-nr236/raku/task-one.rakutest
+# or               raku --optimize=3 -I challenge-nr236 -- test/benchmark-scalabiity.raku --task=task-one --user=rcmlz --max-run-times=1,3,7 --max-problem=10 --v=True --test-before-benchmark=True --out-folder=/tmp nr236; cat /tmp/nr236_task-one.csv
+
+#|[
+You are asked to sell juice each costs $5. 
+You are given an array of bills. 
+You can only sell ONE juice to each customer but make sure you return exact change back. 
+You only have $5, $10 and $20 notes. 
+You do not have any change in hand at first.
+
+- Write a script to find out if it is possible to sell to each customers with correct change.
+]
+our sub solution(@input --> Bool) is export {
+	my $n = @input;
+
+	my %change =
+		5 => 0,
+		10 => 0,
+		20 => 0
+	;
+
+	my $i = 0;
+	while (%change.values).all >= 0 and $i < $n {
+		given @input[$i++] {
+			when 5  { 
+					 	%change<5>++
+				    } 
+			when 10 { 
+					 	%change<5>--; 
+					 	%change<10>++
+					} 
+			when 20 { 
+						if %change<10> {
+					  		%change<10>--
+					  	}else {
+					  		%change<5>--;
+					  		%change<5>--
+					  	}
+					  	%change<5>--
+					} 
+			default { die  "$_ : only 5, 10 and 20 as input is accepted!"}
+		}
+	}
+
+	(%change.values).all >= 0 ?? True !! False
+}
\ No newline at end of file
diff --git a/challenge-236/rcmlz/raku/ch-2.raku b/challenge-236/rcmlz/raku/ch-2.raku
new file mode 100644
index 0000000000..13571552ec
--- /dev/null
+++ b/challenge-236/rcmlz/raku/ch-2.raku
@@ -0,0 +1,36 @@
+unit module rcmlz::raku::task-two:ver<0.0.1>:auth<github:rcmlz>:api<1>;
+
+# run in terminal: raku --optimize=3 -I challenge-nr236/rcmlz/raku/ -- test/challenge-nr236/raku/task-two.rakutest
+# or               raku --optimize=3 -I challenge-nr236 -- test/benchmark-scalabiity.raku --task=task-two --user=rcmlz --max-run-times=1,3,7 --max-problem=10 --v=True --test-before-benchmark=True --out-folder=/tmp nr236; cat /tmp/nr236_task-two.csv
+
+#|[
+You are given an array of unique integers.
+
+- Write a script to determine how many loops are in the given array.
+- To determine a loop: Start at an index and take the number at array[index]
+  and then proceed to that index and continue this until you end up at the starting index.
+]
+our sub solution(@input) is export {
+    my %graph = @input.pairs;
+    my $cycles = 0;
+
+    while %graph.keys.elems {
+        
+        $cycles = $cycles + %graph.grep( -> $entry {$entry.key == $entry.value} );
+
+        %graph = %graph.grep( -> $entry {$entry.key != $entry.value} );        
+
+        my $untouched = %graph.keys.Set;
+
+        for %graph.kv -> $k, $v {
+            if %graph{$v}:exists {
+                %graph{$k} = %graph{$v};
+                $untouched = $untouched ∖ $k;
+            }
+        }
+
+        %graph{$_}:delete for $untouched.keys;
+    }
+
+    return $cycles;
+}
\ No newline at end of file
diff --git a/challenge-236/robert-dicicco/julia/ch-1.jl b/challenge-236/robert-dicicco/julia/ch-1.jl
new file mode 100644
index 0000000000..9650b34e02
--- /dev/null
+++ b/challenge-236/robert-dicicco/julia/ch-1.jl
@@ -0,0 +1,55 @@
+#!/usr/bin/env julia
+#=
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Julia )
+-------------------------------------
+=#
+
+using Printf
+
+bills = [[5, 5, 5, 10, 20], [5, 5, 10, 10, 20],[5, 5, 5, 20]]
+
+for paid in bills
+    @printf("Input: @bills = %s\n", paid)
+    cnt = 1
+    change = 0
+    while cnt <=length(paid)
+        ticket = paid[cnt]
+        change_required = ticket - 5
+        if ticket == 5
+            change += 5
+        elseif ticket == 10
+            change += 0
+        elseif ticket == 20
+            if change_required > change
+                @printf("Output: false\n\n")
+                break
+            else
+                @printf("Output: true\n\n")
+                break
+            end
+            change -= 10
+        end
+        cnt += 1
+    end
+end
+
+#=
+--------------------------------------
+SAMPLE OUTPUT
+julia .\ExactChange.jl
+
+Input: @bills = [5, 5, 5, 10, 20]
+Output: true
+
+Input: @bills = [5, 5, 10, 10, 20]
+Output: false
+
+Input: @bills = [5, 5, 5, 20]
+Output: true
+-------------------------------------
+=#
+
+
diff --git a/challenge-236/robert-dicicco/perl/ch-1.pl b/challenge-236/robert-dicicco/perl/ch-1.pl
new file mode 100644
index 0000000000..be79d7d4de
--- /dev/null
+++ b/challenge-236/robert-dicicco/perl/ch-1.pl
@@ -0,0 +1,56 @@
+#!/usr/bin/env perl
+use v5.38;
+=begin comment
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Perl )
+-------------------------------------
+=cut
+
+my @bills = ([5, 5, 5, 10, 20], [5, 5, 10, 10, 20],[5, 5, 5, 20]);
+
+for my $chg (@bills) {
+    say "Input: \@bills = [@$chg]";
+    my $ln = scalar @$chg;
+    my $cnt = 0;
+    my $change = 0;
+    while ($cnt < @$chg) {
+        my $ticket = $chg->[$cnt];
+        my $change_required = $ticket - 5;
+        if ($ticket == 5){
+            $change += 5;
+        } elsif ($ticket == 10) {
+            $change -= 5;
+            $change += 5;
+        } elsif ($ticket == 20) {
+            if ($change_required > $change){
+                say "Output: false\n";
+                last;
+            } else {
+                say "Output: true\n";
+                last;
+            }
+            $change -= 15;
+            $change += 5;
+        }
+        $cnt++;
+    }
+}
+=begin comment
+--------------------------------------
+SAMPLE OUTPUT
+perl .\ExactChange.pl
+
+Input: @bills = [5 5 5 10 20]
+Output: true
+
+Input: @bills = [5 5 10 10 20]
+Output: false
+
+Input: @bills = [5 5 5 20]
+Output: true
+-------------------------------------
+=cut
+
+
diff --git a/challenge-236/robert-dicicco/powershell/ch-1.psl b/challenge-236/robert-dicicco/powershell/ch-1.psl
new file mode 100644
index 0000000000..ba05daec08
--- /dev/null
+++ b/challenge-236/robert-dicicco/powershell/ch-1.psl
@@ -0,0 +1,53 @@
+<#
+--------------------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Powershell )
+--------------------------------------------------
+#>
+
+$bills = @( (5, 5, 5, 10, 20), (5, 5, 10, 10, 20),(5, 5, 5, 20))
+
+foreach  ($paid in $bills ) {
+    write-host "Input: @bills = [$paid]"
+    $cnt = 0
+    $change = 0
+    $ln = $paid.Length
+    while ( $cnt -lt $ln ) {
+        $ticket = $paid[$cnt]
+        $change_required = $ticket - 5
+        switch ($ticket) {
+            5 {$change += 5}
+            10 {}
+            20 {
+                if ($change_required -gt $change) {
+                    write-host "Output: false`n"
+                    break
+                } else {
+                    write-host "Output: true`n"
+                    break
+                }
+            }
+        }
+        $cnt += 1
+    }
+}
+
+<#
+--------------------------------------------------
+SAMPLE OUTPUT
+.\ExactChange.ps1
+
+Input: @bills = [5 5 5 10 20]
+Output: true
+
+Input: @bills = [5 5 10 10 20]
+Output: false
+
+Input: @bills = [5 5 5 20]
+Output: true
+--------------------------------------------------
+#>
+
+
+
diff --git a/challenge-236/robert-dicicco/python/ch-1.py b/challenge-236/robert-dicicco/python/ch-1.py
new file mode 100644
index 0000000000..7f1521f673
--- /dev/null
+++ b/challenge-236/robert-dicicco/python/ch-1.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+'''
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Python )
+-------------------------------------
+'''
+bills = [[5, 5, 5, 10, 20], [5, 5, 10, 10, 20],[5, 5, 5, 20]]
+
+for paid in bills:
+    print(f"Input: @bills = {paid}")
+    cnt = 0
+    change = 0
+    while cnt < len(paid):
+        ticket = paid[cnt]
+        change_required = ticket - 5
+        if ticket == 5:
+            change += 5
+        elif ticket == 10:
+            change += 0
+        elif ticket == 20:
+            if change_required > change:
+                print("Output: false\n")
+                break
+            else:
+                print("Output: true\n")
+                break
+            change -= 10
+        cnt += 1
+
+'''
+--------------------------------------
+SAMPLE OUTPUT
+python .\ExactChange.py
+
+Input: @bills = [5, 5, 5, 10, 20]
+Output: true
+
+Input: @bills = [5, 5, 10, 10, 20]
+Output: false
+
+Input: @bills = [5, 5, 5, 20]
+Output: true
+-------------------------------------
+'''
+
+
+
+
diff --git a/challenge-236/robert-dicicco/raku/ch-1.raku b/challenge-236/robert-dicicco/raku/ch-1.raku
new file mode 100644
index 0000000000..77664be74b
--- /dev/null
+++ b/challenge-236/robert-dicicco/raku/ch-1.raku
@@ -0,0 +1,56 @@
+#!/usr/bin/env raku
+use v6;
+
+=begin comment
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Raku )
+-------------------------------------
+=end comment
+
+my @bills = ([5, 5, 5, 10, 20], [5, 5, 10, 10, 20],[5, 5, 5, 20]);
+
+for (@bills) -> @chg {
+    say "Input: \@bills = ",@chg;
+    my $cnt = 0;
+    my $change = 0;
+    while ($cnt < @chg.elems) {
+        my $ticket = @chg[$cnt];
+        my $change_required = $ticket - 5;
+        if $ticket == 5 {
+            $change += 5;
+        } elsif $ticket == 10 {
+            $change += 0;
+        } elsif $ticket == 20 {
+            if $change_required > $change {
+                say "Output: false\n";
+                last;
+            } else {
+                say "Output: true\n";
+                last;
+            }
+            $change -= 10;
+        }
+        $cnt++;
+    }
+}
+
+=begin comment
+--------------------------------------
+SAMPLE OUTPUT
+raku .\ExactChange.rk
+
+Input: @bills = [5 5 5 10 20]
+Output: true
+
+Input: @bills = [5 5 10 10 20]
+Output: false
+
+Input: @bills = [5 5 5 20]
+Output: true
+-------------------------------------
+=end comment
+
+
+
diff --git a/challenge-236/robert-dicicco/ruby/ch-1.rb b/challenge-236/robert-dicicco/ruby/ch-1.rb
new file mode 100644
index 0000000000..160a48363f
--- /dev/null
+++ b/challenge-236/robert-dicicco/ruby/ch-1.rb
@@ -0,0 +1,57 @@
+#!/usr/bin/env ruby
+=begin
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Ruby )
+-------------------------------------
+=end
+
+bills = [[5, 5, 5, 10, 20], [5, 5, 10, 10, 20],[5, 5, 5, 20]]
+
+bills.each do |paid|
+    puts("Input: @bills = #{paid}")
+    cnt = 0
+    change = 0
+    while cnt < paid.length()
+        ticket = paid[cnt]
+        change_required = ticket - 5
+        cnt += 1
+        case ticket
+        when 5
+            change += 5
+        when 10
+            # pass
+        when 20
+            if change_required > change
+                puts("Output: false\n\n")
+                break
+            else
+                puts("Output: true\n\n")
+                break
+            end
+            change -= 10
+        end
+    end
+    cnt += 1
+end
+
+=begin
+--------------------------------------
+SAMPLE OUTPUT
+ruby .\ExactChange.rb
+
+Input: @bills = [5, 5, 5, 10, 20]
+Output: true
+
+Input: @bills = [5, 5, 10, 10, 20]
+Output: false
+
+Input: @bills = [5, 5, 5, 20]
+Output: true
+-------------------------------------
+=end
+
+
+
+
diff --git a/challenge-236/robert-dicicco/tcl/ch-1.tcl b/challenge-236/robert-dicicco/tcl/ch-1.tcl
new file mode 100644
index 0000000000..a6e97d6699
--- /dev/null
+++ b/challenge-236/robert-dicicco/tcl/ch-1.tcl
@@ -0,0 +1,58 @@
+#!/usr/bin/env tclsh
+set comment {
+--------------------------------------
+AUTHOR: Robert DiCicco
+DATE  : 2023-09-25
+Challenge 236 Task 01 Exact Change ( Tcl )
+-------------------------------------
+}
+
+set bills { { 5 5 5 10 20 } { 5 5 10 10 20 } { 5 5 5 20 } }
+
+foreach paid $bills {
+    puts "Input: @bills = ($paid)"
+    set cnt 0
+    set change 0
+    set ln [expr [llength $paid]]
+    while { [ expr $cnt ] < $ln } {
+        set ticket [lindex $paid $cnt]
+        set change_required [expr $ticket - 5]
+        switch $ticket {
+            5 {
+                set change [ expr $change + 5 ]
+            }
+            10 {
+            }
+            20 {
+                if { $change_required > $change  } {
+                    puts "Output: false\n"
+                    break
+                } else {
+                    puts "Output: true\n"
+                    break
+                }
+                set change [ expr $change - 10]
+            }
+        }
+        set cnt [expr $cnt + 1]
+    }
+    set cnt 0
+}
+
+set comment {
+--------------------------------------
+SAMPLE OUTPUT
+tclsh .\ExactChange.tcl
+
+Input: @bills = ( 5 5 5 10 20 )
+Output: true
+
+Input: @bills = ( 5 5 10 10 20 )
+Output: false
+
+Input: @bills = ( 5 5 5 20 )
+Output: true
+-------------------------------------
+}
+
+
diff --git a/challenge-236/ulrich-rieke/cpp/ch-2.cpp b/challenge-236/ulrich-rieke/cpp/ch-2.cpp
new file mode 100755
index 0000000000..17a7d6bd94
--- /dev/null
+++ b/challenge-236/ulrich-rieke/cpp/ch-2.cpp
@@ -0,0 +1,38 @@
+#include <iostream>

+#include <vector>

+#include <numeric>

+#include <set>

+#include <algorithm>

+

+//my assumption is that you can always find a loop if the starting array 

+//is a random shuffle of all the indices of a vector from 0 to len - 1 where

+//len is the length of the array. 

+

+int main( ) {

+   std::vector<int> numbers( 20 ) ;

+   std::iota( numbers.begin( ) , numbers.end( ) , 1 ) ;

+   std::random_shuffle( numbers.begin( ) , numbers.end( ) ) ;

+   int loops = 0 ;

+   for ( int pos = 0 ; pos < 20 ; pos++ ) {

+      if ( numbers[ pos ] == pos ) { 

+	 loops++ ;

+      }

+      else {

+	 std::set<int> already_seen ;

+	 int num = numbers[ pos ] ;

+	 auto p = already_seen.insert( num ) ;

+	 while ( p.second ) {

+	    if ( already_seen.find( num ) != already_seen.end( ) ) {

+	       loops++ ;

+	       break ;

+	    }

+	    else {

+	       num = numbers[ num ] ;

+	       p = already_seen.insert( num ) ;

+	    }

+	 }

+      }

+   }

+   std::cout << loops << std::endl ;

+   return 0 ;

+}

diff --git a/challenge-236/ulrich-rieke/rust/ch-2.rs b/challenge-236/ulrich-rieke/rust/ch-2.rs
new file mode 100755
index 0000000000..17724298c3
--- /dev/null
+++ b/challenge-236/ulrich-rieke/rust/ch-2.rs
@@ -0,0 +1,42 @@
+use std::io ;
+use std::collections::HashSet ;
+
+fn main() {
+    println!("Enter some unique positive integers!");
+    println!("They should be a random shuffle of integers from 0 to array length!") ;
+    let mut inline : String = String::new( ) ;
+    io::stdin( ).read_line( &mut inline ).unwrap( ) ;
+    let entered_line : &str = &*inline ;
+    let numbers : Vec<usize> = entered_line.split_whitespace( ).map( | s | 
+	  s.trim( ).parse::<usize>( ).unwrap( ) ).collect( ) ;
+    let mut loops : usize = 0 ;
+    //the strategy is as follows : if a number in the array represents its own 
+    //index, it is a loop in itself , and the number of loops can be increased
+    //otherwise: for every index in the vector, we build a set of numbers we fill
+    //by adding numbers from numbers[current_index]. If we cannot add a number 
+    //to the set because it is already there no loop can be formed at that index.
+    //Otherwise we continue until, eventually, numbers[current_index] == start_index
+    for pos in 0..numbers.len( ) {
+       if numbers[ pos ] == pos {
+	  loops += 1 ;
+       }
+       else {
+	  let mut already_seen : HashSet<usize> = HashSet::new( ) ;
+	  let mut num : usize = numbers[ pos ] ; 
+	  let mut inserted : bool = already_seen.insert( num ) ;
+	  'inner: while inserted {
+	     println!("{:?}" , already_seen ) ;
+	     if already_seen.contains( &pos ) {
+		loops += 1 ;
+		break 'inner ;
+	     }
+	     else {
+		num = numbers[ num ] ;
+		inserted = already_seen.insert( num ) ;
+	     }
+	  }
+       }
+    }
+    println!("{}" , loops) ;
+}
+
diff --git a/challenge-236/wanderdoc/perl/ch-1.pl b/challenge-236/wanderdoc/perl/ch-1.pl
new file mode 100755
index 0000000000..1647898986
--- /dev/null
+++ b/challenge-236/wanderdoc/perl/ch-1.pl
@@ -0,0 +1,70 @@
+#!perl

+use strict;

+use warnings FATAL => qw(all);

+

+=prompt

+You are asked to sell juice each costs $5. You are given an array of bills. You can only sell ONE juice to each customer but make sure you return exact change back. You only have $5, $10 and $20 notes. You do not have any change in hand at first. 

+Write a script to find out if it is possible to sell to each customers with correct change.

+Example 1 Input: @bills = (5, 5, 5, 10, 20) Output: true

+From the first 3 customers, we collect three $5 bills in order.

+From the fourth customer, we collect a $10 bill and give back a $5.

+From the fifth customer, we give a $10 bill and a $5 bill.

+Since all customers got correct change, we output true.

+

+Example 2 Input: @bills = (5, 5, 10, 10, 20) Output: false

+From the first two customers in order, we collect two $5 bills.

+For the next two customers in order, we collect a $10 bill and give back a $5 bill.

+For the last customer, we can not give the change of $15 back because we only have two $10 bills.

+Since not every customer received the correct change, the answer is false.

+=cut

+

+use Test2::V0;

+

+sub exact_change

+{

+     my @bills = @_;

+     my %change;

+     for my $bill ( @bills )

+     {

+          if ( $bill == 5 )

+          {

+               $change{$bill}++;

+          }

+          elsif ( $bill == 10 )

+          {

+               if ( $change{5} > 0 )

+               {

+                    $change{$bill}++;

+                    $change{5}--;

+               }

+               else

+               {

+                    return 'false';

+               }

+          }

+          elsif ( $bill == 20 )

+          {

+               if ( $change{5} > 2 ) 

+               { 

+                    $change{$bill}++; 

+                    $change{5} -= 3; 

+               }

+               elsif ( $change{5} > 0 and $change{10} > 0 )

+               {

+                    $change{$bill}++;

+                    $change{5}--;

+                    $change{10}--;

+               }

+               else

+               {

+                    return 'false';

+               }

+          }

+     }

+     return 'true';

+}

+

+

+is(exact_change(5, 5, 5, 10, 20), 'true', 'Example 1');

+is(exact_change(5, 5, 10, 10, 20), 'false', 'Example 2');

+done_testing();

diff --git a/challenge-236/wanderdoc/perl/ch-2.pl b/challenge-236/wanderdoc/perl/ch-2.pl
new file mode 100755
index 0000000000..df05db485f
--- /dev/null
+++ b/challenge-236/wanderdoc/perl/ch-2.pl
@@ -0,0 +1,102 @@
+#!perl

+use strict;

+use warnings FATAL => qw(all);

+

+=prompt

+You are given an array of unique integers. Write a script to determine how many loops are in the given array.

+To determine a loop: Start at an index and take the number at array[index] and then proceed to that index and continue this until you end up at the starting index.

+

+Example 1 Input: @ints = (4,6,3,8,15,0,13,18,7,16,14,19,17,5,11,1,12,2,9,10)

+Output: 3

+To determine the 1st loop, start at index 0, the number at that index is 4, proceed to index 4, the number at that index is 15, proceed to index 15 and so on until you're back at index 0.

+Loops are as below:

+[4 15 1 6 13 5 0]

+[3 8 7 18 9 16 12 17 2]

+[14 11 19 10]

+Example 2 

+Input: @ints = (0,1,13,7,6,8,10,11,2,14,16,4,12,9,17,5,3,18,15,19)

+Output: 6

+Loops are as below:

+[0]

+[1]

+[13 9 14 17 18 15 5 8 2]

+[7 11 4 6 10 16 3]

+[12]

+[19]

+Example 3 Input: @ints = (9,8,3,11,5,7,13,19,12,4,14,10,18,2,16,1,0,15,6,17)

+Output: 1

+Loop is as below:

+[9 4 5 7 19 17 15 1 8 12 18 6 13 2 3 11 10 14 16 0]

+=cut

+

+use List::Util qw(uniq);

+use Test2::V0;

+

+my @answers =

+(

+     [

+       [4, 15, 1, 6, 13, 5, 0],

+       [3, 8, 7, 18, 9, 16, 12, 17, 2],

+       [14, 11, 19, 10],

+     ],

+     [

+       [0],

+       [1],

+       [13, 9, 14, 17, 18, 15, 5, 8, 2],

+       [7, 11, 4, 6, 10, 16, 3],

+       [12],

+       [19],

+     ],

+     [

+       [9, 4, 5, 7, 19, 17, 15, 1, 8, 12, 18, 6, 13, 2, 3, 11, 10, 14, 16, 0],

+     ]

+);

+

+

+sub count_loops

+{

+     my @arr = @_;

+     die "Not all values are unique!$/" unless @arr = uniq @arr;

+     my $max_idx = $#arr;

+     my @output;

+     my %val_used;

+     BIG_LOOP: for my $i ( 0 .. $#arr )

+     {

+          my $start_value = $arr[$i];

+          next if $val_used{$start_value};

+          my @loop;

+          if ( $start_value == $i )

+          {

+               push @output, [$start_value];

+               $val_used{$start_value}++;

+          }

+          else

+          {

+               my %this_loop_values;

+               push @loop, $start_value;

+               $this_loop_values{$start_value}++;

+               while ( $#loop <= $max_idx )

+               {

+                    my $next_value = $arr[$start_value];

+                    if ( $this_loop_values{$next_value} )

+                    {

+                         push @output, [@loop];

+                         $val_used{$_}++ for @loop;

+                         next BIG_LOOP;

+                    }

+                    else

+                    {

+                         $this_loop_values{$next_value}++;

+                         push @loop, $next_value;

+                         $start_value = $next_value;

+                    }

+               }

+          }

+     }

+     return @output;

+}

+

+is([count_loops(4,6,3,8,15,0,13,18,7,16,14,19,17,5,11,1,12,2,9,10)], $answers[0], 'Example 1');

+is([count_loops(0,1,13,7,6,8,10,11,2,14,16,4,12,9,17,5,3,18,15,19)], $answers[1], 'Example 2');

+is([count_loops(9,8,3,11,5,7,13,19,12,4,14,10,18,2,16,1,0,15,6,17)], $answers[2], 'Example 3');

+done_testing();
\ No newline at end of file