Merge pull request #6392 from Firedrake/rogerbw-challenge-172

Solutions for challenge #172

18 files changed, 1295 insertions, 0 deletions

diff --git a/challenge-172/roger-bell-west/javascript/ch-1.js b/challenge-172/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..17db559d95
--- /dev/null
+++ b/challenge-172/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,97 @@
+#! /usr/bin/node
+
+"use strict"
+
+function deepEqual(a,b)
+{
+    if( (typeof a == 'object' && a != null) &&
+        (typeof b == 'object' && b != null) )
+    {
+        var count = [0,0]
+        for( var key in a) count[0]++
+        for( var key in b) count[1]++
+        if( count[0]-count[1] != 0) {return false}
+        for( var key in a)
+        {
+            if(!(key in b) || !deepEqual(a[key],b[key])) {return false}
+        }
+        for( var key in b)
+        {
+            if(!(key in a) || !deepEqual(b[key],a[key])) {return false}
+        }
+        return true
+    }
+    else
+    {
+        return a === b
+    }
+}
+
+function genprimes(mx) {
+    let primesh=new Set([2,3])
+    for (let i = 6; i <= mx; i += 6) {
+        for (let j = i-1; j <= i+1; j += 2) {
+            if (j <= mx) {
+                primesh.add(j);
+            }
+        }
+    }
+    let q=[2,3,5,7];
+    let p=q.shift();
+    let mr=Math.floor(Math.sqrt(mx));
+    while (p <= mr) {
+        if (primesh.has(p)) {
+            let i=p*p
+            for (let i=p*p; i <= mx; i += p) {
+                primesh.delete(i);
+            }
+        }
+        if (q.length < 2) {
+            q.push(q[q.length-1]+4);
+            q.push(q[q.length-1]+2);
+        }
+        p=q.shift();
+    }
+    let primes=[...primesh];
+    primes.sort(function(a,b) {
+        return a-b;
+    });
+    return primes;
+}
+
+function primepartition (n, divs) {
+    let pl = genprimes(n);
+    let p = [[]];
+    while (p.length > 0) {
+        let pa = p.pop();
+        if (pa.length == divs) {
+            if (pa.reduce((x,y) => x+y, 0) == n) {
+                return pa;
+            }
+        } else {
+            let px = new Set(pa);
+            for (let pq of pl) {
+                if (!px.has(pq)) {
+                    let pb = [...pa];
+                    pb.push(pq);
+                    p.push(pb);
+                }
+            }
+        }
+    }
+    return [n];
+}
+
+if (deepEqual(primepartition(18, 2),[13, 5])) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+
+if (deepEqual(primepartition(19, 3),[11, 5, 3])) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-172/roger-bell-west/javascript/ch-2.js b/challenge-172/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..2f0420ad38
--- /dev/null
+++ b/challenge-172/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,54 @@
+#! /usr/bin/node
+
+"use strict"
+
+function deepEqual(a,b)
+{
+    if( (typeof a == 'object' && a != null) &&
+        (typeof b == 'object' && b != null) )
+    {
+        var count = [0,0]
+        for( var key in a) count[0]++
+        for( var key in b) count[1]++
+        if( count[0]-count[1] != 0) {return false}
+        for( var key in a)
+        {
+            if(!(key in b) || !deepEqual(a[key],b[key])) {return false}
+        }
+        for( var key in b)
+        {
+            if(!(key in a) || !deepEqual(b[key],a[key])) {return false}
+        }
+        return true
+    }
+    else
+    {
+        return a === b
+    }
+}
+
+function fivenumber(n0) {
+    let n = [...n0];
+    n.sort();
+    let nl = n.length - 1;
+    let o = [ n[0] ];
+    for (let quartile = 1; quartile <= 3; quartile++) {
+        let bx = quartile * nl;
+        let base = Math.floor(bx / 4);
+        let v = n[base];
+        if (bx % 4 != 0) {
+            v = (n[base] + n[base+1]) / 2;
+        }
+        o.push(v);
+    }
+    o.push(n[n.length - 1]);
+    return o;
+}
+
+if (deepEqual(fivenumber([0, 0, 1, 2, 63, 61, 27, 13]),
+              [0, 0.5, 7.5, 44, 63])) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-172/roger-bell-west/kotlin/ch-1.kt b/challenge-172/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..fb13b6be60
--- /dev/null
+++ b/challenge-172/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,73 @@
+import kotlin.math.*
+
+fun genprimes(mx: Int): ArrayList<Int> {
+    var primesh=mutableSetOf<Int>()
+    for (i in 2..3) {
+        primesh.add(i)
+    }
+    for (i in 6..mx+1 step 6) {
+        for (j in i-1..i+1 step 2) {
+            if (j <= mx) {
+                primesh.add(j)
+            }
+        }
+    }
+    var q=ArrayDeque(listOf(2,3,5,7))
+    var p=q.removeFirst()
+    val mr=sqrt(mx.toDouble()).toInt()
+    while (p <= mr) {
+        if (primesh.contains(p)) {
+            for (i in p*p..mx step p) {
+                primesh.remove(i)
+            }
+        }
+        if (q.size < 2) {
+            q.add(q.last()+4)
+            q.add(q.last()+2)
+        }
+        p=q.removeFirst()
+    }
+    var primes=ArrayList(primesh.distinct())
+    primes.sort()
+    return primes
+}
+
+fun primepartition(n: Int, divs: Int): ArrayList<Int> {
+    val pl = genprimes(n)
+    var p = ArrayList<ArrayList<Int>>()
+    p.add(ArrayList<Int>())
+    while (p.size > 0) {
+        val pa = p.removeLast()
+        if (pa.size == divs) {
+            if (pa.sum() == n) {
+                return pa
+            }
+        } else {
+            val px = pa.toSet()
+            for (pq in pl) {
+                if (!px.contains(pq)) {
+                    var pb = ArrayList(pa)
+                    pb.add(pq)
+                    p.add(pb)
+                }
+            }
+        }
+    }
+    return arrayListOf(n)
+}
+
+fun main() {
+    if (primepartition(18, 2) == listOf(13, 5)) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    
+    if (primepartition(19, 3) == listOf(11, 5, 3)) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-172/roger-bell-west/kotlin/ch-2.kt b/challenge-172/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..992604f7e3
--- /dev/null
+++ b/challenge-172/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,27 @@
+fun fivenumber(n0: List<Double>): ArrayList<Double> {
+    var n = ArrayList(n0)
+    n.sort()
+    val nl = n.size - 1
+    var o = arrayListOf(n[0])
+    for (quartile in 1..3) {
+        val bx = quartile * nl
+        val base = bx / 4
+        var v = n[base]
+        if (bx % 4 != 0) {
+            v = (n[base] + n[base+1]) / 2.0
+        }
+        o.add(v)
+    }
+    o.add(n[n.size - 1])
+    return o
+}
+
+fun main() {
+    if (fivenumber(listOf(0.0, 0.0, 1.0, 2.0, 63.0, 61.0, 27.0, 13.0)) ==
+            listOf(0.0, 0.5, 7.5, 44.0, 63.0)) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-172/roger-bell-west/lua/ch-1.lua b/challenge-172/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..82e7553e65
--- /dev/null
+++ b/challenge-172/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,111 @@
+#! /usr/bin/lua
+
+-- by Michael Anderson at
+-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
+function recursive_compare(t1,t2)
+  -- Use usual comparison first.
+  if t1==t2 then return true end
+  -- We only support non-default behavior for tables
+  if (type(t1)~="table") then return false end
+  -- They better have the same metatables
+  local mt1 = getmetatable(t1)
+  local mt2 = getmetatable(t2)
+  if( not recursive_compare(mt1,mt2) ) then return false end
+
+  -- Check each key-value pair
+  -- We have to do this both ways in case we miss some.
+  -- TODO: Could probably be smarter and not check those we've 
+  -- already checked though!
+  for k1,v1 in pairs(t1) do
+    local v2 = t2[k1]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+  for k2,v2 in pairs(t2) do
+    local v1 = t1[k2]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+
+  return true  
+end
+
+function genprimes(mx)
+   local primesh = {}
+   for i = 2, 3 do
+      primesh[i] = true
+   end
+   for i = 6, mx, 6 do
+      for j = i-1, i+1, 2 do
+         if j <= mx then
+            primesh[j]=true
+         end
+      end
+   end
+   local q={2,3,5,7}
+   local p=table.remove(q,1)
+   local mr=math.floor(math.sqrt(mx))
+   while p <= mr do
+      if primesh[p] ~= nil then
+         for i = p*p,mx,p do
+            primesh[i] = nil
+         end
+      end
+      if #q < 2 then
+         table.insert(q,q[#q]+4)
+         table.insert(q,q[#q]+2)
+      end
+      p=table.remove(q,1)
+   end
+   local primes = {}
+   for k,v in pairs(primesh) do
+      table.insert(primes,k)
+   end
+   table.sort(primes)
+   return primes
+end
+
+function primepartition(n, divs)
+   local pl = genprimes(n)
+   local p = {{}}
+   while #p > 0 do
+      local pa = table.remove(p)
+      if #pa == divs then
+         local sum = 0
+         for i,v in ipairs(pa) do
+            sum = sum + v
+         end
+         if sum == n then
+            return pa
+         end
+      else
+         local px = {}
+         for i,v in ipairs(pa) do
+            px[v] = true
+         end
+         for i,pq in ipairs(pl) do
+            if px[pq] == nil then
+               local pb = {}
+               for j,pk in ipairs(pa) do
+                  table.insert(pb,pk)
+               end
+               table.insert(pb,pq)
+               table.insert(p,pb)
+            end
+         end
+      end
+   end
+   return {n}
+end
+
+if recursive_compare(primepartition(18,2), {13, 5}) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if recursive_compare(primepartition(19,3), {11, 5, 3}) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-172/roger-bell-west/lua/ch-2.lua b/challenge-172/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..0477026669
--- /dev/null
+++ b/challenge-172/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,60 @@
+#! /usr/bin/lua
+
+-- by Michael Anderson at
+-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
+function recursive_compare(t1,t2)
+  -- Use usual comparison first.
+  if t1==t2 then return true end
+  -- We only support non-default behavior for tables
+  if (type(t1)~="table") then return false end
+  -- They better have the same metatables
+  local mt1 = getmetatable(t1)
+  local mt2 = getmetatable(t2)
+  if( not recursive_compare(mt1,mt2) ) then return false end
+
+  -- Check each key-value pair
+  -- We have to do this both ways in case we miss some.
+  -- TODO: Could probably be smarter and not check those we've 
+  -- already checked though!
+  for k1,v1 in pairs(t1) do
+    local v2 = t2[k1]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+  for k2,v2 in pairs(t2) do
+    local v1 = t1[k2]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+
+  return true  
+end
+
+function fivenumber(n0)
+   local n = {}
+   for i,v in ipairs(n0) do
+      table.insert(n,v)
+   end
+   table.sort(n)
+   local nl = #n - 1
+   local o = {n[1]}
+   for quartile = 1,3 do
+      local bx = quartile * nl
+      local base = math.floor(bx / 4)
+      local v = n[base+1]
+      if bx % 4 ~= 0 then
+         v = (n[base+1] + n[base+2]) / 2
+      end
+      table.insert(o,v)
+   end
+   table.insert(o,n[#n])
+   return o
+end
+
+if recursive_compare(
+   fivenumber({0., 0., 1., 2., 63., 61., 27., 13.}),
+   {0., 0.5, 7.5, 44., 63.}
+) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-172/roger-bell-west/perl/ch-1.pl b/challenge-172/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..0de4ff4f1d
--- /dev/null
+++ b/challenge-172/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,38 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 2;
+use Math::Prime::Util qw(primes);
+use List::Util qw(sum);
+
+is_deeply(primepartition(18, 2),
+          [13, 5],
+          'example 1');
+
+is_deeply(primepartition(19, 3),
+          [11, 5, 3],
+          'example 2');
+
+sub primepartition($n, $divs) {
+  my @pl = @{primes($n)};
+  my @p = ([]);
+  while (scalar @p > 0) {
+    my $pa = pop @p;
+    if (scalar @{$pa} == $divs) {
+      if (sum(@{$pa}) == $n) {
+        return $pa;
+      }
+    } else {
+      my %px = map {$_ => 1} @{$pa};
+      foreach my $pq (@pl) {
+        unless (exists $px{$pq}) {
+          push @p,[@{$pa},$pq];
+        }
+      }
+    }
+  }
+  return [$n];
+}
diff --git a/challenge-172/roger-bell-west/perl/ch-2.pl b/challenge-172/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..ed01eaff50
--- /dev/null
+++ b/challenge-172/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,28 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 1;
+
+is_deeply(fivenumber((0.0, 0.0, 1.0, 2.0, 63.0, 61.0, 27.0, 13.0)),
+          [0.0, 0.5, 7.5, 44.0, 63.0],
+          'example 1');
+
+sub fivenumber(@n0) {
+  my @n = sort(@n0);
+  my $nl = scalar @n - 1;
+  my @o = ($n[0]);
+  foreach my $quartile (1..3) {
+    my $bx = $quartile * $nl;
+    my $base = int($bx / 4);
+    my $v = $n[$base];
+    if ($bx % 4 != 0) {
+      $v = ($n[$base] + $n[$base+1]) / 2
+    }
+    push @o,$v;
+  }
+  push @o,$n[-1];
+  return \@o;
+}
diff --git a/challenge-172/roger-bell-west/postscript/ch-1.ps b/challenge-172/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..77c4b30ff1
--- /dev/null
+++ b/challenge-172/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,278 @@
+%!PS
+
+% begin included library code
+% see https://github.com/Firedrake/postscript-libraries/
+/genprimes {
+    6 dict begin
+    /mx exch def
+    /primesh mx dict def
+    2 1 3 {
+        primesh exch true put
+    } for
+    6 6 mx 1 add {
+        dup 1 sub exch 1 add 2 exch {
+            dup mx le {
+                primesh exch true put
+            } {
+                pop
+            } ifelse
+        } for
+    } for
+    /q [ 3 5 7 ] def
+    /qi 0 def
+    /p 2 def
+    /mr mx sqrt cvi def
+    {
+        p mr le not {
+            exit
+        } if
+        primesh p known {
+            p dup mul p mx {
+                primesh exch undef
+            } for
+        } if
+        q length qi sub 2 le {
+            /q q q q length 1 sub get 4 add apush def
+            /q q q q length 1 sub get 2 add apush def
+        } if
+        /p q qi get def
+        /qi qi 1 add def
+    } loop
+    primesh keys
+    end
+} bind def
+
+/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
+
+/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 {
+    /test.count test.count 1 add def
+    {
+        /test.pass test.pass 1 add def
+    } {
+        ( ) print
+        test.count (....) cvs print
+        (-fail) print
+    } ifelse
+} bind def
+
+/toset { % array -> dict of (value, true)
+    << exch
+       {
+           true
+       } forall
+    >>
+} 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 { % [ a c b ] -> [ a b c ]
+    1 dict begin
+    /arr exch def
+    0 arr length 1 sub quicksort.main
+    arr
+    end
+} bind def
+
+/keys { % dict -> array of dict keys
+    [ exch
+      {
+          pop
+      } forall
+    ]
+} 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 ge {
+                exit
+            } if
+        } loop
+        {
+            /j j 1 sub def
+            arr j get pivot le {
+                exit
+            } if
+        } loop
+        i j ge {
+            j
+            exit
+        } if
+        i j quicksort.swap
+    } loop
+    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
+
+/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
+
+/apop.right { % [a b c] -> [a b] c
+    [ exch aload length 1 add 1 roll ] exch
+} bind def
+
+/apush.right { % [a b] c -> [a b c]
+    exch
+    [ exch aload length 2 add -1 roll ]
+} bind def
+
+
+/apush { apush.right } bind def
+
+
+% end included library code
+
+/primepartition {
+    6 dict begin
+    /divs exch def
+    /n exch def
+    /p [ 0 array ] def
+    /pl n genprimes quicksort def
+    [ n ]
+    {
+        p length 0 eq {
+            exit
+        } if
+        p apop.right /pa exch def /p exch def
+        pa length divs eq {
+            pa { add } reduce n eq {
+                pop pa
+                exit
+            } if
+        } {
+            /px pa toset def
+            pl {
+                /pq exch def
+                px pq known not {
+                    /p p [ pa aload pop pq ] apush.right def
+                } if
+            } forall
+        } ifelse
+    } loop
+    end
+} bind def
+
+(primepartition) test.start
+18 2 primepartition [ 13 5 ] deepeq test
+19 3 primepartition [ 11 5 3 ] deepeq test
+test.end
diff --git a/challenge-172/roger-bell-west/postscript/ch-2.ps b/challenge-172/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..6d4f0b6aa2
--- /dev/null
+++ b/challenge-172/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,186 @@
+%!PS
+
+% begin included library code
+% see https://github.com/Firedrake/postscript-libraries/
+/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 { % [ a c b ] -> [ a b c ]
+    1 dict begin
+    /arr exch def
+    0 arr length 1 sub quicksort.main
+    arr
+    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
+
+/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
+
+/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.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 ge {
+                exit
+            } if
+        } loop
+        {
+            /j j 1 sub def
+            arr j get pivot le {
+                exit
+            } if
+        } loop
+        i j ge {
+            j
+            exit
+        } if
+        i j quicksort.swap
+    } loop
+    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
+
+
+% end included library code
+
+/fivenumber {
+    4 dict begin
+    /n exch quicksort def
+    /nl n length 1 sub def
+    [
+        n 0 get
+        1 1 3 {
+            nl mul /bx exch def
+            /base bx 4 idiv def
+            n base get
+            bx 4 mod 0 ne {
+                n base 1 add get add 2.0 div
+            } if
+        } for
+        n nl get
+    ]
+    end
+} bind def
+
+(fivenumber) test.start
+[0.0 0.0 1.0 2.0 63.0 61.0 27.0 13.0] fivenumber [ 0.0 0.5 7.5 44.0 63.0 ] deepeq test
+test.end
diff --git a/challenge-172/roger-bell-west/python/ch-1.py b/challenge-172/roger-bell-west/python/ch-1.py
new file mode 100755
index 0000000000..1db86de4d6
--- /dev/null
+++ b/challenge-172/roger-bell-west/python/ch-1.py
@@ -0,0 +1,56 @@
+#! /usr/bin/python3
+
+import unittest
+
+from math import sqrt,floor,log
+from collections import deque
+
+def genprimes(mx):
+  primesh=set(range(2,4))
+  for i in range(6,mx+2,6):
+    for j in range(i-1,i+2,2):
+      if j <= mx:
+        primesh.add(j)
+  q=deque([2,3,5,7])
+  p=q.popleft()
+  mr=floor(sqrt(mx))
+  while p <= mr:
+    if p in primesh:
+      for i in range(p*p,mx+1,p):
+        primesh.discard(i)
+    if len(q) < 2:
+      q.append(q[-1]+4)
+      q.append(q[-1]+2)
+    p=q.popleft()
+  primes=list(primesh)
+  primes.sort()
+  return primes
+
+def primepartition(n, divs):
+  pl = genprimes(n)
+  p = [[]]
+  while len(p) > 0:
+    pa = p.pop()
+    if len(pa) == divs:
+      if sum(pa) == n:
+        return pa
+    else:
+      px = set(pa)
+      for pq in pl:
+        if pq not in px:
+          pb = pa.copy()
+          pb.append(pq)
+          p.append(pb)
+  return [n]
+
+class TestPrimepartition(unittest.TestCase):
+
+        def test_ex1(self):
+          self.assertEqual(primepartition(18, 2),
+                           [13, 5],'example 1')
+
+        def test_ex2(self):
+          self.assertEqual(primepartition(19, 3),
+                           [11, 5, 3],'example 1')
+</