Merge pull request #9232 from Firedrake/rogerbw-challenge-247

RogerBW solutions for challenge no. 247

21 files changed, 1213 insertions, 0 deletions

diff --git a/challenge-247/roger-bell-west/javascript/ch-1.js b/challenge-247/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..e63be00da6
--- /dev/null
+++ b/challenge-247/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,52 @@
+#! /usr/bin/node
+
+"use strict"
+
+function secretsanta(name) {
+    let family = [];
+    for (let n of name) {
+        let surname = n.split(" ");
+        family.push(surname[surname.length - 1]);
+    }
+    let receivers = new Set(Array(name.length).fill().map((element, index) => index));
+    let gifting = [];
+    for (let giver = 0; giver < name.length; giver++) {
+        let done = false;
+        let r = 0;
+        for (let recipient of receivers) {
+            if (family[giver] != family[recipient]) {
+                r = recipient;
+                done = true;
+                break;
+            }
+        }
+        if (!done) {
+            for (let recipient of receivers) {
+                if (recipient != giver) {
+                    r = recipient;
+                    break;
+                }
+            }
+        }
+        receivers.delete(r)
+        gifting.push([name[giver], name[r]]);
+    }
+    for (let p of gifting) {
+        console.log("%s -> %s", p[0], p[1]);
+    }
+    console.log("");
+    return true;
+}
+
+if (secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar', 'Mrs. Anwar', 'Mr. Conway', 'Mr. Cross'])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar'])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-247/roger-bell-west/javascript/ch-2.js b/challenge-247/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..6ba8875493
--- /dev/null
+++ b/challenge-247/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,32 @@
+#! /usr/bin/node
+
+"use strict"
+
+function mostfrequentletterpair(s) {
+    let f = new Map;
+    for (let i = 0; i < s.length - 1; i++) {
+        let pair = s.substring(i, i + 2);
+        if (f.has(pair)) {
+            f.set(pair,f.get(pair)+1);
+        } else {
+            f.set(pair,1);
+        }
+    }
+    const m = Math.max(...f.values());
+    let l = Array.from(f.keys()).filter(i => f.get(i) == m);
+    l.sort();
+    return l[0];
+}
+
+if (mostfrequentletterpair('abcdbca') == 'bc') {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (mostfrequentletterpair('cdeabeabfcdfabgcd') == 'ab') {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-247/roger-bell-west/kotlin/ch-1.kt b/challenge-247/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..9aab0e29d7
--- /dev/null
+++ b/challenge-247/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,50 @@
+fun secretsanta(name: List<String>): Boolean {
+    val family: List<String> = name.map{n -> n.split(" ").last()}.toList()
+    var receivers = generateSequence(0) { it + 1 }.take(name.size).toMutableSet()
+    var gifting = ArrayList<List<String>>()
+    for (giver in 0 .. name.size - 1) {
+        var done = false
+        var r = 0
+        for (recipient in receivers) {
+            if (family[giver] != family[recipient]) {
+                r = recipient
+                done = true
+                break
+            }
+        }
+        if (!done) {
+            for (recipient in receivers) {
+                if (giver != recipient) {
+                    r = recipient
+                    break
+                }
+            }
+        }
+        receivers.remove(r)
+        gifting.add(listOf(name[giver], name[r]))
+    }
+    for (p in gifting) {
+        print(p[0])
+        print(" -> ")
+        println(p[1])
+    }
+    println("")
+    return true;
+}
+
+fun main() {
+
+    if (secretsanta(listOf("Mr. Wall", "Mrs. Wall", "Mr. Anwar", "Mrs. Anwar", "Mr. Conway", "Mr. Cross"))) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (secretsanta(listOf("Mr. Wall", "Mrs. Wall", "Mr. Anwar"))) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-247/roger-bell-west/kotlin/ch-2.kt b/challenge-247/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..6ada6d0aa3
--- /dev/null
+++ b/challenge-247/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,31 @@
+  fun mostfrequentletterpair(s: String): String {
+    var f = mutableMapOf<String, Int>()
+    for ( i in 0 .. s.length - 2 ) {
+      val ss = s.substring(i,i + 2)
+      var nv = 1
+      if (f.containsKey(ss)) {
+        nv = 1 + f.getValue(ss)
+      }
+      f[ss] = nv
+    }
+    val m = f.values.maxOrNull()!!
+    val l = f.keys.filter{i -> f[i] == m}.toList().sorted()
+    return l[0]
+  }
+
+fun main() {
+
+    if (mostfrequentletterpair("abcdbca") == "bc") {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (mostfrequentletterpair("cdeabeabfcdfabgcd") == "ab") {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-247/roger-bell-west/lua/ch-1.lua b/challenge-247/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..9b1bf20f97
--- /dev/null
+++ b/challenge-247/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,69 @@
+#! /usr/bin/lua
+
+-- bart at https://stackoverflow.com/questions/1426954/split-string-in-lua
+function split(inputstr, sep)
+   sep=sep or '%s'
+   local t={}
+   for field,s in string.gmatch(inputstr, "([^"..sep.."]*)("..sep.."?)") do
+      table.insert(t,field)
+      if s=="" then
+         return t
+      end
+   end
+end
+
+function secretsanta(name)
+   local family = {}
+   for _, n in ipairs(name) do
+      local surname = split(n, " ")
+      table.insert(family, surname[#surname])
+   end
+   local receivers = {}
+   for n = 1, #name do
+      receivers[n] = true
+   end
+   local gifting = {}
+   for giver = 1, #name do
+      local done = false
+      local r = 0
+      for recipient, _ in pairs(receivers) do
+         if family[giver] ~= family[recipient] then
+            r = recipient
+            done = true
+            break
+         end
+      end
+      if not done then
+         for recipient, _ in pairs(receivers) do
+            if giver ~= recipient then
+               r = recipient
+               break
+            end
+         end
+      end
+      receivers[r] = nil
+      table.insert(gifting, {name[giver], name[r]})
+   end
+   for _, p in ipairs(gifting) do
+      io.write(p[1])
+      io.write(" -> ")
+      print(p[2])
+   end
+   print("")
+   return true
+end
+
+if secretsanta({"Mr. Wall", "Mrs. Wall", "Mr. Anwar", "Mrs. Anwar", "Mr. Conway", "Mr. Cross"}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if secretsanta({"Mr. Wall", "Mrs. Wall", "Mr. Anwar"}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-247/roger-bell-west/lua/ch-2.lua b/challenge-247/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..e3bccde3d7
--- /dev/null
+++ b/challenge-247/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,40 @@
+#! /usr/bin/lua
+
+function mostfrequentletterpair(s)
+   local f = {}
+   local m = 0
+   for i = 0,string.len(s) - 1 do
+      pair = string.sub(s, i, i + 1)
+      if f[pair] == nil then
+         f[pair] = 1
+      else
+         f[pair] = f[pair] + 1
+         if f[pair] > m then
+            m = f[pair]
+         end
+      end
+   end
+   local l = {}
+   for k, v in pairs(f) do
+      if v == m then
+         table.insert(l, k)
+      end
+   end
+   table.sort(l)
+   return l[1]
+end
+
+if mostfrequentletterpair("abcdbca") == "bc" then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if mostfrequentletterpair("cdeabeabfcdfabgcd") == "ab" then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-247/roger-bell-west/perl/ch-1.pl b/challenge-247/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..79bec4edbe
--- /dev/null
+++ b/challenge-247/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,45 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 2;
+
+is(secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar', 'Mrs. Anwar', 'Mr. Conway', 'Mr. Cross']), 1, 'example 1');
+is(secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar']), 1, 'example 2');
+
+sub secretsanta($name) {
+  my @family;
+  foreach my $n (@{$name}) {
+    push @family, (split(' ', $n))[-1];
+  }
+  my %receivers = map {$_ => 1} (0 .. $#{$name});
+  my @gifting;
+  foreach my $giver (0 .. $#{$name}) {
+    my $done = 0;
+    my $r = 0;
+    foreach my $recipient (keys %receivers) {
+      if ($family[$giver] ne $family[$recipient]) {
+        $r = $recipient;
+        $done = 1;
+        last;
+      }
+    }
+    if (!$done) {
+      foreach my $recipient (keys %receivers) {
+        if ($recipient != $giver) {
+          $r = $recipient;
+          last;
+        }
+      }
+    }
+    delete $receivers{$r};
+    push @gifting, [$name->[$giver], $name->[$r]];
+  }
+  foreach my $p (@gifting) {
+    print("$p->[0] -> $p->[1]\n");
+  }
+  print "\n";
+  return 1;
+}
diff --git a/challenge-247/roger-bell-west/perl/ch-2.pl b/challenge-247/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..cb015363d1
--- /dev/null
+++ b/challenge-247/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,23 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 2;
+
+is(mostfrequentletterpair('abcdbca'), 'bc', 'example 1');
+is(mostfrequentletterpair('cdeabeabfcdfabgcd'), 'ab', 'example 2');
+
+use List::Util qw(max);
+
+sub mostfrequentletterpair($s) {
+  my %f;
+  foreach my $i (0 .. length($s) - 2) {
+    my $pair = substr($s, $i, 2);
+    $f{$pair}++;
+  }
+  my $m = max(values %f);
+  my @l = sort {$a cmp $b} grep {$f{$_} == $m} keys %f;
+  return $l[0];
+}
diff --git a/challenge-247/roger-bell-west/postscript/ch-1.ps b/challenge-247/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..a10b6de394
--- /dev/null
+++ b/challenge-247/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,192 @@
+%!PS
+
+% begin included library code
+% see https://codeberg.org/Firedrake/postscript-libraries/
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/strsplit % (ajbjc) (j) -> [ (a) (b) (c) ]
+{
+    1 dict begin
+    /sep exch def
+    [ exch
+      {
+          dup length 0 eq {
+              pop
+              exit
+          } {
+              sep search {
+                  exch pop
+                  dup length 0 eq {
+                      pop
+                  } {
+                      exch
+                  } ifelse
+              } {
+                  ()
+              } ifelse
+          } ifelse
+      } loop
+    ]
+    end
+} bind def
+
+/deepeq {
+    2 dict begin
+    /a exch def
+    /b exch def
+    a type b type eq {
+        a type /dicttype eq {
+            a length b length eq {
+                <<
+                    a {
+                        pop
+                        true
+                    } forall
+                    b {
+                        pop
+                        true
+                    } forall
+                >>
+                true exch
+                {
+                    pop
+                    dup a exch known {
+                        dup b exch known {
+                            dup a exch get exch b exch get deepeq not {
+                                pop false
+                            } if
+                        } {
+                            false
+                        } ifelse
+                    } {
+                        false
+                    } ifelse
+                } forall
+            } {
+                false
+            } ifelse
+        } {
+            a type dup /arraytype eq exch /stringtype eq or {
+                a length b length eq {
+                    true
+                    0 1 a length 1 sub {
+                        dup a exch get exch b exch get deepeq not {
+                            pop false
+                            exit
+                        } if
+                    } for
+                } {
+                    false
+                } ifelse
+            } {
+                a b eq
+            } ifelse
+        } ifelse
+    } {
+        false
+    } ifelse
+    end
+} bind def
+
+/apush.right { % [a b] c -> [a b c]
+    exch
+    [ exch aload length 2 add -1 roll ]
+} 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
+
+/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
+
+/toset { % array -> dict of (value, true)
+    << exch
+       {
+           true
+       } forall
+    >>
+} bind def
+
+
+% end included library code
+
+/secretsanta {
+    0 dict begin
+    /name exch def
+    /family [
+        name {
+            ( ) strsplit 1 get
+        } forall
+    ] def
+    /receivers [ 0 1 name length 1 sub { } for ] toset def
+    /gifting 0 array def
+    0 1 name length 1 sub {
+        /giver exch def
+        /done false def
+        /r 0 def
+        receivers keys {
+            /recipient exch def
+            family giver get family recipient get deepeq not {
+                /r recipient def
+                /done true def
+                exit
+            } if
+        } forall
+        done not {
+            receivers keys {
+                /recipient exch def
+                recipient giver ne {
+                    /r recipient def
+                    exit
+                } if
+            } forall
+        } if
+        receivers r undef
+        /gifting gifting [ name giver get name r get ] apush.right def
+    } for
+    gifting {
+        /p exch def
+        p 0 get print
+        ( -> ) print
+        p 1 get =
+    } forall
+    () =
+    true
+    end
+} bind def
+
+(secretsanta) test.start
+[(Mr. Wall) (Mrs. Wall) (Mr. Anwar) (Mrs. Anwar) (Mr. Conway) (Mr. Cross)] secretsanta test
+[(Mr. Wall) (Mrs. Wall) (Mr. Anwar)] secretsanta test
+test.end
diff --git a/challenge-247/roger-bell-west/postscript/ch-2.ps b/challenge-247/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..b9b43b7204
--- /dev/null
+++ b/challenge-247/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,272 @@
+%!PS
+
+% begin included library code
+% see https://codeberg.org/Firedrake/postscript-libraries/
+/reduce { % array proc -> value
+    2 dict begin
+    /p exch def
+    /a exch def
+    a 0 get
+    1 1 a length 1 sub {
+        a exch get
+        p
+    } for
+    end
+} bind def
+
+/filter { % array proc(bool) -> array
+    1 dict begin
+    /p exch def
+    [ exch
+      {
+          dup p not
+          {
+              pop
+          } if
+      } forall
+    ]
+    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
+
+/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
+
+/quicksort {
+    { quicksort.cmp } quicksort.with_comparator
+} 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
+
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/deepeq {
+    2 dict begin
+    /a exch def
+    /b exch def
+    a type b type eq {
+        a type /dicttype eq {
+            a length b length eq {
+                <<
+                    a {
+                        pop
+                        true
+                    } forall
+                    b {
+                        pop
+                        true
+                    } forall
+                >>
+                true exch
+                {
+                    pop
+                    dup a exch known {
+                        dup b exch known {
+                            dup a exch get exch b exch get deepeq not {
+                                pop false
+                            } if
+                        } {
+                            false
+                        } ifelse
+                    } {
+                        false
+                    } ifelse
+                } forall
+            } {
+                false
+            } ifelse
+        } {
+            a type dup /arraytype eq exch /stringtype eq or {
+                a length b length eq {
+                    true
+                    0 1 a length 1 sub {
+                        dup a exch get exch b exch get deepeq not {
+                            pop false
+                            exit
+                        } if
+                    } for
+                } {
+                    false
+                } ifelse
+            } {
+                a b eq
+            } ifelse
+        } ifelse
+    } {
+        false
+    } ifelse
+    end
+} bind def
+
+/map { % array proc -> array
+    2 dict begin
+    /p exch def
+    [ exch
+      {
+          p
+      } forall
+    ]
+    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
+
+/dget {
+    3 1 roll
+    2 copy
+    known {
+        get exch pop
+    } {
+        pop pop
+    } ifelse
+} bind def
+
+/values { % dict -> array of dict values
+    [ exch
+      {
+          exch pop
+      } forall
+    ]
+} bind def
+
+/keys { % dict -> array of dict keys
+    [ exch
+      {
+          pop
+      } forall
+    ]
+} bind def
+
+/quicksort.cmp {
+    2 copy
+    lt {
+        pop pop -1
+    } {
+        gt {
+            1
+        } {
+            0
+        } ifelse
+    } ifelse
+} bind def
+
+/listmax {
+    { max } reduce
+} 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
+
+
+% end included library code
+
+/mostfrequentletterpair {
+    0 dict begin
+    /s exch def
+    /f 0 dict def
+    0 1 s length 2 sub {
+        s exch 2 getinterval /pair exch def
+        f pair 0 dget 1 add f exch pair exch put
+    } for
+    /m f values listmax def
+    f keys
+    { f exch get m eq } filter
+    { (..) cvs } map
+    quicksort
+    0 get
+    end
+} bind def
+
+(mostfrequentletterpair) test.start
+(abcdbca) mostfrequentletterpair (bc) deepeq test
+(cdeabeabfcdfabgcd) mostfrequentletterpair (ab) deepeq test
+test.end
diff --git a/challenge-247/roger-bell-west/python/ch-1.py b/challenge-247/roger-bell-west/python/ch-1.py
new file mode 100755
index 0000000000..930bf8cccc
--- /dev/null
+++ b/challenge-247/roger-bell-west/python/ch-1.py
@@ -0,0 +1,40 @@
+#! /usr/bin/python3
+
+def secretsanta(name):
+  family = []
+  for n in name:
+    surname = n.split(" ")[-1]
+    family.append(surname)
+  receivers = set(range(len(name)))
+  gifting = []
+  for giver in range(len(name)):
+    done = False
+    r = 0
+    for recipient in receivers:
+      if family[giver] != family[recipient]:
+        r = recipient
+        done = True
+        break
+    if not done:
+      for recipient in receivers:
+        if recipient != giver:
+          r = recipient
+          break
+    receivers.discard(r)
+    gifting.append([name[giver], name[r]])
+  for p in gifting:
+    print(p[0] + " -> " + p[1])
+  print("")
+  return True
+
+import unittest
+
+class TestSecretsanta(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(secretsanta(["Mr. Wall", "Mrs. Wall", "Mr. Anwar", "Mrs. Anwar", "Mr. Conway", "Mr. Cross"]), True, 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(secretsanta(["Mr. Wall", "Mrs. Wall", "Mr. Anwar"]), True, 'example 2')
+
+unittest.main()
diff --git a/challenge-247/roger-bell-west/python/ch-2.py b/challenge-247/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..1f152b7172
--- /dev/null
+++ b/challenge-247/roger-bell-west/python/ch-2.py
@@ -0,0 +1,25 @@
+#! /usr/bin/python3
+
+from collections import defaultdict
+
+def mostfrequentletterpair(s):
+  f = defaultdict(lambda: 0)
+  for i in range(len(s) - 1):
+    pair = s[i] + s[i+1]
+    f[pair] += 1
+  m = max(f.values())
+  l = [i for i in f.keys() if f[i] == m]
+  l.sort()
+  return l[0]
+
+import unittest
+
+class TestMostfrequentletterpair(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(mostfrequentletterpair("abcdbca"), "bc", 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(mostfrequentletterpair("cdeabeabfcdfabgcd"), "ab", 'example 2')
+
+unittest.main()
diff --git a/challenge-247/roger-bell-west/raku/ch-1.p6 b/challenge-247/roger-bell-west/raku/ch-1.p6
new file mode 100755
index 0000000000..e8e14bf92a
--- /dev/null
+++ b/challenge-247/roger-bell-west/raku/ch-1.p6
@@ -0,0 +1,43 @@
+#! /usr/bin/raku
+
+use Test;
+
+plan 2;
+
+is(secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar', 'Mrs. Anwar', 'Mr. Conway', 'Mr. Cross']), True, 'example 1');
+is(secretsanta(['Mr. Wall', 'Mrs. Wall', 'Mr. Anwar']), True, 'example 2');
+
+sub secretsanta(@name) {
+    my @family;
+    for @name -> $n {
+        push @family, comb(/\w+/, $n)[*-1];
+    }
+    my %receivers = SetHash(0 .. @name.end);
+    my @gifting;
+    for (0 .. @name.end) -> $giver {
+        my $done = False;
+        my $r = 0;
+        for %receivers.keys -> $recipient {
+            if (@family[$giver] ne @family[$recipient]) {
+                $r = $recipient;
+                $done = True;
+                last;
+            }
+        }
+        if (!$done) {
+            for %receivers.keys -> $recipient {
+                if ($recipient != $giver) {
+                    $r = $recipient;
+                    last;
+                }
+            }
+        }
+        %receivers{$r}:delete;
+        push @gifting, [@name[$giver], @name[$r]];
+    }
+    for @gifting -> @p {
+        say("@p[0] -> @p[1]");
+    }
+    say "";
+    return True;
+}
diff --git a/challenge-247/roger-bell-west/raku/ch-2.p6 b/challenge-247/roger-bell-west/raku/ch-2.p6
new file mode 100755
index 0000000000..4e9fc0839b
--- /dev/null
+++ b/challenge-247/roger-bell-west/raku/ch-2.p6
@@ -0,0 +1,19 @@
+#! /usr/bin/raku
+
+use Test;
+
+plan 2;
+
+is(mostfrequentletterpair('abcdbca'), 'bc', 'example 1');
+is(mostfrequentletterpair('cdeabeabfcdfabgcd'), 'ab', 'example 2');
+
+sub mostfrequentletterpair($s) {
+    my %f;
+    for (0 .. chars($s) - 2) -> $i {
+        my $pair = substr($s, $i, 2);
+        %f{$pair}++;
+    }
+    my $m = max(values %f);
+    my @l = %f.keys.grep({%f{$_} == $m}).sort({$^a cmp $^b});
+    return @l[0];
+}
diff --git a/challenge-247/roger-bell-west/ruby/ch-1.rb b/challenge-247/roger-bell-west/ruby/ch-1.rb
new file mode 100755
index 0000000000..1831fed5fe
--- /dev/null
+++ b/challenge-247/roger-bell-west/ruby/ch-1.rb
@@ -0,0 +1,52 @@
+#! /usr/bin/ruby