RogerBW solutions for challenge no. 236

21 files changed, 1461 insertions, 0 deletions

diff --git a/challenge-236/roger-bell-west/javascript/ch-1.js b/challenge-236/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..98b6a4569e
--- /dev/null
+++ b/challenge-236/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,72 @@
+#! /usr/bin/node
+
+"use strict"
+
+function Reserve(vv) {
+    let r = Object.create(Reserve.methods);
+    let vq = vv.sort(function(a, b) {
+        return b - a;
+    });
+    r.values = vq;
+    r.counts = [];
+    r.vm = new Map;
+    for (let i = 0; i < vq.length; i++) {
+        r.counts.push(0);
+        r.vm.set(vq[i], i);
+    }
+    return r;
+}
+
+Reserve.methods = {
+    makechange(price, tendered) {
+        let val = 0;
+        for (let note of tendered) {
+            if (!this.vm.has(note)) {
+                return false;
+            }
+            this.counts[this.vm.get(note)]++;
+            val += note;
+        }
+        if (val < price) {
+            return false;
+        }
+        val -= price;
+        for (let bid = 0; bid < this.values.length; bid++) {
+            while (val >= this.values[bid] && this.counts[bid] > 0) {
+                val -= this.values[bid];
+                this.counts[bid]--;
+            }
+        }
+        return (val == 0);
+    }
+}
+
+function exactchange(a) {
+    var reserve = Reserve([5, 10, 20])
+    for (let tendered of a) {
+        if (!reserve.makechange(5, [tendered])) {
+            return false;
+        }
+    }
+    return true;
+}
+
+
+if (exactchange([5, 5, 5, 10, 20])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (!exactchange([5, 5, 10, 10, 20])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (exactchange([5, 5, 5, 20])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-236/roger-bell-west/javascript/ch-2.js b/challenge-236/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..2af581a1ea
--- /dev/null
+++ b/challenge-236/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,54 @@
+#! /usr/bin/node
+
+"use strict"
+
+function arrayloops(a) {
+    let loop_id = 0;
+    let loops = new Map;
+    for (let origin = 0; origin < a.length; origin++) {
+        if (!loops.has(origin)) {
+            let li = 0;
+            let thisloop = new Set;
+            let x = origin;
+            while (true) {
+                if (x >= a.length) {
+                    break;
+                }
+                thisloop.add(x);
+                x = a[x];
+                if (loops.has(x)) {
+                    li = loops.get(x);
+                    break;
+                }
+                if (thisloop.has(x)) {
+                    loop_id += 1;
+                    li = loop_id;
+                    break;
+                }
+            }
+            for (let i of thisloop) {
+                loops.set(i, li);
+            }
+        }
+    }
+    return loop_id;
+}
+
+if (arrayloops([4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5, 11, 1, 12, 2, 9, 10]) == 3) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (arrayloops([0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19]) == 6) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (arrayloops([9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17]) == 1) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-236/roger-bell-west/kotlin/ch-1.kt b/challenge-236/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..e72f15fedc
--- /dev/null
+++ b/challenge-236/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,72 @@
+class Reserve(vls: List<Int>)  {
+    var vll: ArrayList<Int> = ArrayList(0)
+    var counts: ArrayList<Int> = ArrayList(0)
+    var vm = mutableMapOf<Int, Int>()
+
+    init {
+        var vq = ArrayList(vls)
+        vq.sort()
+        vq.reverse()
+        vll = vq
+        for (i in 1..vq.size) {
+            counts.add(0)
+        }
+        vq.forEachIndexed {i, v -> vm.put(v, i)}
+    }
+
+    fun makechange(price: Int, tendered: List<Int>): Boolean {
+        var vl = 0
+        for (note in tendered) {
+            if (!vm.contains(note)) {
+                return false
+            }
+            counts[vm.getValue(note)] += 1
+            vl += note
+        }
+        if (vl < price) {
+            return false
+        }
+        vl -= price
+        for (bid in 0..vll.size-1) {
+            while (vl >= vll[bid] && counts[bid] > 0) {
+                vl -= vll[bid]
+                counts[bid] -= 1
+            }
+        }
+        return (vl == 0)
+    }
+}
+
+fun exactchange(a: List<Int>): Boolean {
+    var reserve = Reserve(listOf(5, 10, 20))
+    for (tendered in a) {
+        if (!reserve.makechange(5, listOf(tendered))) {
+            return false
+        }
+    }
+    return true
+}
+
+
+fun main() {
+
+    if (exactchange(listOf(5, 5, 5, 10, 20))) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (!exactchange(listOf(5, 5, 10, 10, 20))) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (exactchange(listOf(5, 5, 5, 20))) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-236/roger-bell-west/kotlin/ch-2.kt b/challenge-236/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..dc176509dd
--- /dev/null
+++ b/challenge-236/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,54 @@
+fun arrayloops(a: List<Int>): Int {
+    var loop_id = 0
+    var loops = mutableMapOf<Int, Int>()
+    for (origin in 0..a.size-1) {
+        if (!loops.contains(origin)) {
+            var li = 0
+            var thisloop = mutableSetOf<Int>()
+            var x = origin
+            while (true) {
+                if (x >= a.size) {
+                    break
+                }
+                thisloop.add(x)
+                x = a[x]
+                if (loops.contains(x)) {
+                    li = loops.getValue(x)
+                    break
+                }
+                if (thisloop.contains(x)) {
+                    loop_id += 1
+                    li = loop_id
+                    break
+                }
+            }
+            for (i in thisloop) {
+                loops.put(i, li)
+            }
+        }
+    }
+    return loop_id
+}
+
+fun main() {
+
+    if (arrayloops(listOf(4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5, 11, 1, 12, 2, 9, 10)) == 3) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (arrayloops(listOf(0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19)) == 6) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (arrayloops(listOf(9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17)) == 1) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-236/roger-bell-west/lua/ch-1.lua b/challenge-236/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..85014cd27d
--- /dev/null
+++ b/challenge-236/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,87 @@
+#! /usr/bin/lua
+
+-- by hookenz at
+-- https://stackoverflow.com/questions/9168058/how-to-dump-a-table-to-console
+function dump(o)
+   if type(o) == 'table' then
+      local s = '{ '
+      for k,v in pairs(o) do
+         if type(k) ~= 'number' then k = '"'..k..'"' end
+         s = s .. '['..k..'] = ' .. dump(v) .. ','
+      end
+      return s .. '} '
+   else
+      return tostring(o)
+   end
+end
+
+Reserve = {values = {}, counts = {}, vm = {}}
+
+function Reserve:new(vv)
+   local o = {}
+   self.__index = self
+   setmetatable(o,self)
+   o.values = vv
+   table.sort(o.values, function (aa, bb) return bb < aa end)
+   o.counts = {}
+   o.vm = {}
+   for i, n in ipairs(o.values) do
+      table.insert(o.counts, 0)
+      o.vm[n] = i
+   end
+   return o
+end
+
+function Reserve:makechange(price, tendered)
+   local val = 0
+   for _, note in ipairs(tendered) do
+      if self.vm[note] == nil then
+         return false
+      end
+      self.counts[self.vm[note]] = self.counts[self.vm[note]] + 1
+      val = val + note
+   end
+   if val < price then
+      return false
+   end
+   val = val - price
+   for bid = 1, #self.values do
+      while val >= self.values[bid] and self.counts[bid] > 0 do
+         val = val - self.values[bid]
+         self.counts[bid] = self.counts[bid] - 1
+      end
+   end
+   return (val == 0)
+end
+
+function exactchange(a)
+   local reserve = Reserve:new({5, 10, 20})
+   for _, tendered in ipairs(a) do
+      if not reserve:makechange(5, {tendered}) then
+         return false
+      end
+   end
+   return true
+end
+
+if exactchange({5, 5, 5, 10, 20}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if not exactchange({5, 5, 10, 10, 20}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if exactchange({5, 5, 5, 20}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-236/roger-bell-west/lua/ch-2.lua b/challenge-236/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..5dbb9294be
--- /dev/null
+++ b/challenge-236/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,55 @@
+#! /usr/bin/lua
+
+function arrayloops(a)
+   local loop_id = 0
+   local loops = {}
+   for _i, origin in ipairs(a) do
+      if loops[origin] == nil then
+         local li = 0
+         local thisloop = {}
+         local x = origin
+         while true do
+            if x < 0 or x >= #a then
+               break
+            end
+            thisloop[x] = true
+            x = a[x + 1]
+            if loops[x] ~= nil then
+               li = loops[x]
+               break
+            end
+            if thisloop[x] ~= nil then
+               loop_id = loop_id + 1
+               li = loop_id
+               break
+            end
+         end
+         for i, _t in pairs(thisloop) do
+            loops[i] = li
+         end
+      end
+   end
+   return loop_id
+end
+
+if arrayloops({4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5, 11, 1, 12, 2, 9, 10}) == 3 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if arrayloops({0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19}) == 6 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if arrayloops({9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17}) == 1 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-236/roger-bell-west/perl/ch-1.pl b/challenge-236/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..e1c98df3e5
--- /dev/null
+++ b/challenge-236/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,59 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 3;
+
+is(exactchange([5, 5, 5, 10, 20]), 1, 'example 1');
+is(exactchange([5, 5, 10, 10, 20]), 0, 'example 2');
+is(exactchange([5, 5, 5, 20]), 1, 'example 3');
+
+sub exactchange($a) {
+  my $reserve = Reserve->new([5, 10, 20]);
+  foreach my $tendered (@{$a}) {
+    unless ($reserve->makechange(5, [$tendered])) {
+      return 0;
+    }
+  }
+  return 1;
+}
+
+package Reserve;
+
+sub new($class, $init) {
+  my $self = {
+    vall => [sort {$b <=> $a} @{$init}],
+    counts => [(0) x scalar @{$init}],
+  };
+  bless $self, $class;
+  my %vm;
+  foreach my $n (0..$#{$self->{vall}}) {
+    $vm{$self->{vall}[$n]} = $n;
+  }
+  $self->{vm} = \%vm;
+  return $self;
+}
+
+sub makechange($self, $price, $tendered) {
+  my $val = 0;
+  foreach my $note (@{$tendered}) {
+    unless (exists $self->{vm}{$note}) {
+      return 0;
+    }
+    $self->{counts}[$self->{vm}{$note}]++;
+    $val += $note;
+  }
+  if ($val < $price) {
+    return 0;
+  }
+  $val -= $price;
+  foreach my $bid (0..$#{$self->{vall}}) {
+    while ($val >= $self->{vall}[$bid] && $self->{counts}[$bid] > 0) {
+      $val -= $self->{vall}[$bid];
+      $self->{counts}[$bid]--;
+    }
+  }
+  return ($val == 0);
+}
diff --git a/challenge-236/roger-bell-west/perl/ch-2.pl b/challenge-236/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..1ef37df3e3
--- /dev/null
+++ b/challenge-236/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,43 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 3;
+
+is(arrayloops([4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5, 11, 1, 12, 2, 9, 10]), 3, 'example 1');
+is(arrayloops([0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19]), 6, 'example 2');
+is(arrayloops([9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17]), 1, 'example 3');
+
+sub arrayloops($a) {
+  my $loop_id = 0;
+  my %loops;
+  foreach my $origin (0..$#{$a}) {
+    unless (exists $loops{$origin}) {
+      my $li = 0;
+      my %thisloop;
+      my $x = $origin;
+      while (1) {
+        if ($x < 0 || $x > $#{$a}) {
+          last;
+        }
+        $thisloop{$x} = 1;
+        $x = $a->[$x];
+        if (exists $loops{$x}) {
+          $li = $loops{$x};
+          last;
+        }
+        if (exists $thisloop{$x}) {
+          $loop_id++;
+          $li = $loop_id;
+          last;
+        }
+      }
+      foreach my $i (keys %thisloop) {
+        $loops{$i} = $li;
+      }
+    }
+  }
+  return $loop_id;
+}
diff --git a/challenge-236/roger-bell-west/postscript/ch-1.ps b/challenge-236/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..b2cb52dcd6
--- /dev/null
+++ b/challenge-236/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,221 @@
+%!PS
+
+% begin included library code
+% see https://codeberg.org/Firedrake/postscript-libraries/
+/quicksort.cmp {
+    2 copy
+    lt {
+        pop pop -1
+    } {
+        gt {
+            1
+        } {
+            0
+        } ifelse
+    } ifelse
+} bind def
+
+/quicksort.main { % lo hi -> (null)
+    3 dict begin
+    /hi exch def
+    /lo exch def
+    /xit false def
+    lo 0 lt {
+        /xit true def
+    } if
+    hi 0 lt {
+        /xit true def
+    } if
+    lo hi ge {
+        /xit true def
+    } if
+    xit not {
+        /p quicksort.partition def
+        lo p quicksort.main
+        p 1 add hi quicksort.main
+    } if
+    end
+} bind def
+
+/quicksort {
+    { quicksort.cmp } quicksort.with_comparator
+} bind def
+
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/quicksort.partition {
+    3 dict begin
+    /pivot arr hi lo add 2 idiv get def
+    /i lo 1 sub def
+    /j hi 1 add def
+    {
+        {
+            /i i 1 add def
+            arr i get pivot cmp 0 ge {
+                exit
+            } if
+        } loop
+        {
+            /j j 1 sub def
+            arr j get pivot cmp 0 le {
+                exit
+            } if
+        } loop
+        i j ge {
+            j
+            exit
+        } if
+        i j quicksort.swap
+    } loop
+    end
+} bind def
+
+/quicksort.swap {
+    2 dict begin
+    /bi exch def
+    /ai exch def
+    arr ai get
+    arr bi get
+    arr exch ai exch put
+    arr exch bi exch put
+    end
+} bind def
+
+/quicksort.with_comparator { % [ a c b ] { comparator } -> [ a b c ]
+    2 dict begin
+    /cmp exch def
+    /arr exch def
+    arr length 0 gt {
+        0 arr length 1 sub quicksort.main
+    } if
+    arr
+    end
+} bind def
+
+/test {
+    /test.count test.count 1 add def
+    {
+        /test.pass test.pass 1 add def
+    } {
+        ( ) print
+        test.count (....) cvs print
+        (-fail) print
+    } ifelse
+} bind def
+
+/test.end {
+    ( ) print
+    test.count 0 gt {
+        (Passed ) print
+        test.pass (...) cvs print
+        (/) print
+        test.count (...) cvs print
+        ( \() print
+        test.pass 100 mul test.count idiv (...) cvs print
+        (%\)) print
+        (\r\n) print
+    } if
+} bind def
+
+/reverse {
+    1 dict begin
+    dup length /l exch def
+    [ exch
+      aload pop
+      2 1 l {
+          -1 roll
+      } for
+    ]
+    end
+} bind def
+
+
+% end included library code
+
+/reserve.new {
+    0 dict begin
+    /self 3 dict def
+    quicksort reverse self exch /values exch put
+    self /counts [ self (values) get length { 0 } repeat ] put
+    /vm self (values) get length dict def
+    0 1 self (values) get length 1 sub {
+        dup
+        self (values) get exch get
+        exch
+        vm 3 1 roll
+        put
+    } for
+    self (vm) vm put
+    self
+    end
+} bind def
+
+/reserve.makechange {
+    0 dict begin
+    /tendered exch def
+    /price exch def
+    /self exch def
+    /val 0 def
+    true
+    1 {
+        tendered {
+            /note exch def
+            self (vm) get note known not {
+                pop false
+                exit
+            } if
+            self (counts) get self (vm) get note get get 1 add
+            self (counts) get self (vm) get note get 3 -1 roll put
+            /val val note add def
+        } forall
+        dup not {
+            exit
+        } if
+        val price lt {
+            pop false
+            exit
+        } if
+        /val val price sub def
+        0 1 self (values) get length 1 sub {
+            /bid exch def
+            {
+                val self (values) get bid get lt {
+                    exit
+                } if
+                self (counts) get bid get 0 le {
+                    exit
+                } if
+                /val val self (values) get bid get sub def
+                self (counts) get dup bid get 1 sub bid exch put
+            } loop
+        } for
+    } repeat
+    val 0 eq and
+    end
+} bind def
+
+/exactchange {
+    0 dict begin
+    /reserve [5 10 20] reserve.new def
+    true exch
+    {
+        /tendered exch def
+        reserve 5 [ tendered ] reserve.makechange not {
+            pop false
+            exit
+        } if
+    } forall
+    end
+} bind def
+
+[ 5 10 20 ] reserve.new
+
+(exactchange) test.start
+[5 5 5 10 20] exactchange test
+[5 5 10 10 20] exactchange not test
+[5 5 5 20] exactchange test
+test.end
diff --git a/challenge-236/roger-bell-west/postscript/ch-2.ps b/challenge-236/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..45b04c6137
--- /dev/null
+++ b/challenge-236/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,87 @@
+%!PS
+
+% begin included library code
+% see https://codeberg.org/Firedrake/postscript-libraries/
+/keys { % dict -> array of dict keys
+    [ exch
+      {
+          pop
+      } forall
+    ]
+} bind def
+
+/test.end {
+    ( ) print
+    test.count 0 gt {
+        (Passed ) print
+        test.pass (...) cvs print
+        (/) print
+        test.count (...) cvs print
+        ( \() print
+        test.pass 100 mul test.count idiv (...) cvs print
+        (%\)) print
+        (\r\n) print
+    } if
+} bind def
+
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/test {
+    /test.count test.count 1 add def
+    {
+        /test.pass test.pass 1 add def
+    } {
+        ( ) print
+        test.count (....) cvs print
+        (-fail) print
+    } ifelse
+} bind def
+
+
+% end included library code
+
+/arrayloops {
+    0 dict begin
+    /a exch def
+    /loop_id 0 def
+    /loops 0 dict def
+    a {
+        /origin exch def
+        loops origin known not {
+            /li 0 def
+            /thisloop 0 dict def
+            /x origin def
+            {
+                x 0 lt x a length ge or {
+                    exit
+                } if
+                thisloop x true put
+                /x a x get def
+                loops x known {
+                    /li loops x get def
+                    exit
+                } if
+                thisloop x known {
+                    /loop_id loop_id 1 add def
+                    /li loop_id def
+                    exit
+                } if
+            } loop
+            thisloop keys {
+                loops exch li put
+            } forall
+        } if
+    } forall
+    loop_id
+    end
+} bind def
+
+(arrayloops) test.start
+[4 6 3 8 15 0 13 18 7 16 14 19 17 5 11 1 12 2 9 10] arrayloops 3 eq test
+[0 1 13 7 6 8 10 11 2 14 16 4 12 9 17 5 3 18 15 19] arrayloops 6 eq test
+[9 8 3 11 5 7 13 19 12 4 14 10 18 2 16 1 0 15 6 17] arrayloops 1 eq test
+test.end
diff --git a/challenge-236/roger-bell-west/python/ch-1.py b/challenge-236/roger-bell-west/python/ch-1.py
new file mode 100755
index 0000000000..638c1ca054
--- /dev/null
+++ b/challenge-236/roger-bell-west/python/ch-1.py
@@ -0,0 +1,49 @@
+#! /usr/bin/python3
+
+class Reserve(object):
+  def __init__(self, _vv):
+    _vq = _vv
+    _vq.sort()
+    _vq.reverse()
+    _vm = dict()
+    for i, v in enumerate(_vq):
+      _vm[v] = i
+    self.values = _vq
+    self.counts = [0] * len(_vv)
+    self.vm = _vm
+
+  def makechange(self, price, tendered):
+    val = 0
+    for bill in tendered:
+      if bill not in self.vm:
+        return False
+      self.counts[self.vm.get(bill)] += 1
+      val += bill
+    val -= price
+    for bid in range(len(self.values)):
+      while val >= self.values[bid] and self.counts[bid] > 0:
+        val -= self.values[bid]
+        self.counts[bid] -= 1
+    return (val == 0)
+
+def exactchange(a):
+  reserve = Reserve([5, 10, 20])
+  for tendered in a:
+    if not reserve.makechange(5, [tendered]):
+      return False
+  return True
+
+import unittest
+
+class TestExactchange(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(exactchange([5, 5, 5, 10, 20]), True, 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(exactchange([5, 5, 10, 10, 20]), False, 'example 2')
+
+  def test_ex3(self):
+    self.assertEqual(exactchange([5, 5, 5, 20]), True, 'example 3')
+
+unittest.main()
diff --git a/challenge-236/roger-bell-west/python/ch-2.py b/challenge-236/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..d00cdd365a
--- /dev/null
+++ b/challenge-236/roger-bell-west/python/ch-2.py
@@ -0,0 +1,40 @@
+#! /usr/bin/python3
+
+def arrayloops(a):
+  loop_id = 0
+  loops = dict()
+  for origin in range(len(a)):
+    if origin not in loops:
+      li = 0
+      thisloop = set()
+      x = origin
+      while True:
+        if x < 0 or x >= len(a):
+          break
+        thisloop.add(x)
+        x = a[x]
+        if x in loops:
+          li = loops[x]
+          break
+        if x in thisloop:
+          loop_id += 1
+          li = loop_id
+          break
+    for i in thisloop:
+      loops[i] = li
+  return loop_id
+
+import unittest
+
+class TestArrayloops(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(arrayloops([4, 6, 3, 8, 15, 0, 13, 18, 7, 16, 14, 19, 17, 5, 11, 1, 12, 2, 9, 10]), 3, 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(arrayloops([0, 1, 13, 7, 6, 8, 10, 11, 2, 14, 16, 4, 12, 9, 17, 5, 3, 18, 15, 19]), 6, 'example 2')
+
+  def test_ex3(self):
+    self.assertEqual(arrayloops([9, 8, 3, 11, 5, 7, 13, 19, 12, 4, 14, 10, 18, 2, 16, 1, 0, 15, 6, 17]), 1, 'example 3')
+
+unittest.main()
diff --git a/challenge-236/roger-bell-west/raku/ch-1.p6 b/challenge-236/roger-bell-west/raku/ch-1.p6
new file mode 100755
index 0000000000..cafe4c4b6d
--- /dev/null
+++ b/challenge-236/roger-bell-west/raku/ch-1.p6
@@ -0,0 +1,56 @@
+#! /usr/bin/raku
+
+use Test;
+
+plan 3;
+
+is(exactchange([5, 5, 5, 10, 20]), True, 'example 1');
+is(exactchange([5, 5, 10, 10, 20]), False, 'example 2');
+is(exactchange([5, 5, 5, 20]), True, 'example 3');
+
+class Reserve {
+    has @!values;
+    has @!counts;
+    has %!vm;
+
+    method TWEAK(:@notes) {
+        my @vq = @notes.sort({$^b <=> $^a});
+        for (0..@vq.end) -> $i {
+            %!vm{@vq[$i]} = $i;
+        }
+        @!values = @vq;
+        @!counts = 0 xx @vq.elems;
+    }
+
+    method makechange($price, @tendered) {
+        my $val = 0;
+        for @tendered -> $note {
+            unless (%!vm{$note}:exists) {
+                return False;
+            }
+            @!counts[%!vm{$note}]++;
+            $val += $note;
+        }
+        if ($val < $price) {
+            return False;
+        }
+        $val -= $price;
+        for 0..@!values.end -> $bid {
+            while ($val >= @!values[$bid] && @!counts[$bid] > 0) {
+                $val -= @!values[$bid];
+                @!counts[$bid]--;
+            }
+        }
+        return ($val == 0);
+    }
+}
+
+sub exactchange(@a) {
+    my $reserve = Reserve.new(notes => [5, 10, 20]);
+    for @a -> $tendered {
+        unless ($reserve.makechange(5, [$tendered])) {
+            return False;
+        }
+    }
+    return True;
+}
diff --git a/challenge-236/roger-bell-west/raku/ch-2.p6 b/challenge-236/roger-bell-west/raku/ch-2.p6
new file mode 100755
index 0000000000..95a5128639
--- /dev/null
+++ b/