Merge pull request #11130 from Firedrake/rogerbw-challenge-294

RogerBW solutions for challenge no. 294

23 files changed, 1672 insertions, 0 deletions

diff --git a/challenge-294/roger-bell-west/crystal/ch-1.cr b/challenge-294/roger-bell-west/crystal/ch-1.cr
new file mode 100755
index 0000000000..edb64abd9a
--- /dev/null
+++ b/challenge-294/roger-bell-west/crystal/ch-1.cr
@@ -0,0 +1,48 @@
+#! /usr/bin/crystal
+
+
+def consecutivesequence(a)
+  b = a.sort
+  mxlen = 0
+  here = 0
+  while true
+    (here + 1).upto(b.size - 1) do |there|
+      if b[there] != there - here + b[here]
+        l = there - here
+        if l > mxlen
+          mxlen = l
+        end
+        here = there
+        break
+      end
+      if there == b.size - 1
+        l = there - here + 1
+        if l > mxlen
+          mxlen = l
+        end
+        here = there
+        break
+      end
+    end
+    if here >= b.size - 1
+      break
+    end
+  end
+  if mxlen < 2
+    mxlen = -1
+  end
+  mxlen
+end
+
+require "spec"
+describe "consecutivesequence" do
+  it "test_ex1" do
+    consecutivesequence([10, 4, 20, 1, 3, 2]).should eq 4
+  end
+  it "test_ex2" do
+    consecutivesequence([0, 6, 1, 8, 5, 2, 4, 3, 0, 7]).should eq 9
+  end
+  it "test_ex3" do
+    consecutivesequence([10, 30, 20]).should eq -1
+  end
+end
diff --git a/challenge-294/roger-bell-west/crystal/ch-2.cr b/challenge-294/roger-bell-west/crystal/ch-2.cr
new file mode 100755
index 0000000000..af1f265cea
--- /dev/null
+++ b/challenge-294/roger-bell-west/crystal/ch-2.cr
@@ -0,0 +1,33 @@
+#! /usr/bin/crystal
+
+def nextpermutation(a)
+  b = a.sort
+  flag = false
+  out = [] of Int32
+  b.permutations.each do |px|
+    if out.size == 0
+      out = px
+    end
+    if flag
+      out= px
+      break
+    end
+    if px == a
+      flag = true
+    end
+  end
+  out
+end
+
+require "spec"
+describe "nextpermutation" do
+  it "test_ex1" do
+    nextpermutation([1, 2, 3]).should eq [1, 3, 2]
+  end
+  it "test_ex2" do
+    nextpermutation([2, 1, 3]).should eq [2, 3, 1]
+  end
+  it "test_ex3" do
+    nextpermutation([3, 1, 2]).should eq [3, 2, 1]
+  end
+end
diff --git a/challenge-294/roger-bell-west/javascript/ch-1.js b/challenge-294/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..c8932a7825
--- /dev/null
+++ b/challenge-294/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,58 @@
+#! /usr/bin/node
+
+"use strict"
+
+function consecutivesequence(a){
+    let b = [...a];
+    b.sort(function(aa, bb) {
+        return aa - bb;
+    });
+    let mxlen = 0;
+    let here = 0;
+    while (true) {
+        for (let there = here + 1; there <= b.length - 1; there++) {
+            if (b[there] != there - here + b[here]) {
+                const l = there - here;
+                if (l > mxlen) {
+                    mxlen = l;
+                }
+                here = there;
+                break;
+            }
+            if (there == b.length - 1) {
+                const l = there - here + 1;
+                if (l > mxlen) {
+                    mxlen = l;
+                }
+                here = there;
+                break;
+            }
+        }
+        if (here >= b.length - 1) {
+            break;
+        }
+    }
+    if (mxlen < 2) {
+        mxlen = -1;
+    }
+    return mxlen;
+}
+
+if (consecutivesequence([10, 4, 20, 1, 3, 2]) == 4) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (consecutivesequence([0, 6, 1, 8, 5, 2, 4, 3, 0, 7]) == 9) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (consecutivesequence([10, 30, 20]) == -1) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-294/roger-bell-west/javascript/ch-2.js b/challenge-294/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..7a699e38a2
--- /dev/null
+++ b/challenge-294/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,125 @@
+#! /usr/bin/node
+
+"use strict"
+
+// by Frank Tan
+// https://stackoverflow.com/questions/38400594/javascript-deep-comparison
+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 permute(a) {
+    let out = [];
+    let n=a.length;
+    let c=[];
+    for (let i = 0; i < n; i++) {
+        c.push(0);
+    }
+    out.push([...a]);
+    let i=0;
+    while (true) {
+        if (i >= n) {
+            break;
+        }
+        if (c[i] < i) {
+            if (i % 2 == 0) {
+                [a[0],a[i]] = [a[i],a[0]];
+            } else {
+                [a[c[i]],a[i]] = [a[i],a[c[i]]];
+            }
+            out.push([...a]);
+            c[i]++;
+            i=0;
+        } else {
+            c[i]=0;
+            i++;
+        }
+    }
+    return out;
+}
+
+function nextpermutation(a) {
+    let b = [...a];
+    b.sort(function(aa, bb) {
+        return aa - bb;
+    });
+    let flag = false;
+    let out = [];
+    let pp = permute(b);
+    pp.sort(function(i, j) {
+        let ix = 0;
+        let res = 1;
+        while (true) {
+            if (ix >= i.length && ix >= j.length) {
+                break;
+            }
+            if (ix < i.length && ix >= j.length) {
+                res = 1;
+                break;
+            }
+            if (ix >= i.length && ix < j.length) {
+                res = -1;
+                break;
+            }
+            if (i[ix] != j[ix]) {
+                res = i[ix] - j[ix];
+                break;
+            }
+            ix++;
+        }
+        return res
+    });
+    for (let px of pp) {
+        if (out.length == 1) {
+            out = px;
+        }
+        if (flag) {
+            out = px
+            flag = false;
+        }
+        if (deepEqual(px, a)) {
+            flag = true;
+        }
+    }
+    return out
+}
+
+if (deepEqual(nextpermutation([1, 2, 3]), [1, 3, 2])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (deepEqual(nextpermutation([2, 1, 3]), [2, 3, 1])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (deepEqual(nextpermutation([3, 1, 2]), [3, 2, 1])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-294/roger-bell-west/kotlin/ch-1.kt b/challenge-294/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..e07b9cde63
--- /dev/null
+++ b/challenge-294/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,55 @@
+fun consecutivesequence(a: List<Int>): Int {
+    val b = a.sorted()
+    var mxlen = 0
+    var here = 0
+    while (true) {
+        for (there in here + 1 .. b.size - 1) {
+            if (b[there] != there - here + b[here]) {
+                val l = there - here
+                if (l > mxlen) {
+                    mxlen = l
+                }
+                here = there
+                break
+            }
+            if (there == b.size - 1) {
+                val l = there - here + 1
+                if (l > mxlen) {
+                    mxlen = l
+                }
+                here = there
+                break
+            }
+        }
+        if (here >= b.size - 1) {
+            break
+        }
+    }
+    if (mxlen < 2) {
+        mxlen = -1
+    }
+    return mxlen
+}
+
+fun main() {
+
+    if (consecutivesequence(listOf(10, 4, 20, 1, 3, 2)) == 4) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (consecutivesequence(listOf(0, 6, 1, 8, 5, 2, 4, 3, 0, 7)) == 9) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (consecutivesequence(listOf(10, 30, 20)) == -1) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-294/roger-bell-west/kotlin/ch-2.kt b/challenge-294/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..99d6b20d35
--- /dev/null
+++ b/challenge-294/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,107 @@
+fun permute(aa: List<Int>): ArrayList<List<Int>> {
+    var a = ArrayList<Int>()
+    for (i in aa) {
+        a.add(i)
+    }
+    var out = ArrayList<List<Int>>()
+    val n = a.size
+    var c = ArrayList<Int>();
+    for (i in 0..n-1) {
+        c.add(0)
+    }
+    out.add(a.toList())
+    var i = 0
+    while (true) {
+        if (i >= n) {
+            break
+        }
+        if (c[i] < i) {
+            if (i % 2 == 0) {
+                val tmp = a[0]
+                a[0] = a[i]
+                a[i] = tmp
+            } else {
+                val tmp = a[c[i]]
+                a[c[i]] = a[i]
+                a[i] = tmp
+            }
+            out.add(a.toList())
+            c[i] += 1
+            i = 0
+        } else {
+            c[i] = 0
+            i += 1
+        }
+    }
+    return out
+}
+
+fun nextpermutation(a: List<Int>): List<Int> {
+    val b = a.sorted()
+    var flag = false
+    var out = listOf(0)
+    val listComparator = Comparator {
+        i: List<Int>, j: List<Int> ->
+            var ix = 0
+        var res = false
+        while (true) {
+            if (ix >= i.size && ix >= j.size) {
+                break
+            }
+            if (ix < i.size && ix >= j.size) {
+                res = true
+                break
+            }
+            if (ix >= i.size && ix < j.size) {
+                res = false
+                break
+            }
+            if (i[ix] != j[ix]) {
+                res = i[ix] < j[ix]
+                break
+            }
+            ix += 1
+        }
+        if (res) {
+            -1
+        } else {
+            1
+        }
+    }
+    for (px in permute(b).sortedWith(listComparator)) {
+        if (out.size == 1) {
+            out = px
+        }
+        if (flag) {
+            out = px
+            flag = false
+        }
+        if (px == a) {
+            flag = true
+        }
+    }
+    return out
+}
+
+  fun main() {
+
+    if (nextpermutation(listOf(1, 2, 3)) == listOf(1, 3, 2)) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (nextpermutation(listOf(2, 1, 3)) == listOf(2, 3, 1)) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    print(" ")
+    if (nextpermutation(listOf(3, 1, 2)) == listOf(3, 2, 1)) {
+        print("Pass")
+    } else {
+        print("Fail")
+    }
+    println("")
+
+}
diff --git a/challenge-294/roger-bell-west/lua/ch-1.lua b/challenge-294/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..605d27309d
--- /dev/null
+++ b/challenge-294/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,67 @@
+#! /usr/bin/lua
+function deepcopy(src)
+   local dst = {}
+   for k, v in pairs(src) do
+      if type(v) == "table" then
+         v = deepcopy(v)
+      end
+      dst[k] = v
+   end
+   return dst
+end
+
+function consecutivesequence(a)
+   local b = deepcopy(a)
+   table.sort(b)
+   local mxlen = 0
+   local here = 1
+   while true do
+      for there = here + 1, #b do
+         if b[there] ~= there - here + b[here] then
+            local l = there - here
+            if l > mxlen then
+               mxlen = l
+            end
+            here = there
+            break
+         end
+         if there == #b then
+            local l = there - here + 1
+            if l > mxlen then
+               mxlen = l
+            end
+            here = there
+            break
+         end
+      end
+      if here >= #b then
+         break
+      end
+   end
+   if mxlen < 2 then
+      mxlen = -1
+   end
+   return mxlen
+end
+
+if consecutivesequence({10, 4, 20, 1, 3, 2}) == 4 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if consecutivesequence({0, 6, 1, 8, 5, 2, 4, 3, 0, 7}) == 9 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if consecutivesequence({10, 30, 20}) == -1 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-294/roger-bell-west/lua/ch-2.lua b/challenge-294/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..a96ec89499
--- /dev/null
+++ b/challenge-294/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,131 @@
+#! /usr/bin/lua
+
+-- by Michael Anderson at
+-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
+-- modified by Roger
+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
+  -- Build list of all keys
+  local kk = {}
+  for k1, _ in pairs(t1) do
+     kk[k1] = true
+  end
+  for k2, _ in pairs(t2) do
+     kk[k2] = true
+  end
+  -- Check each key that exists in at least one table
+  for _, k in ipairs(kk) do
+     if (not recursive_compare(t1[k], t2[k])) then
+        return false
+     end
+  end
+  return true
+end
+function permute(a)
+   local out = {}
+   local n = #a
+   local c = {}
+   for i = 1,n do
+      table.insert(c, 1)
+   end
+   table.insert(out, deepcopy(a))
+   local i=1
+   while true do
+      if i > n then
+         break
+      end
+      if c[i] < i then
+         if i % 2 == 1 then
+            a[1],a[i] = a[i],a[1]
+         else
+            a[c[i]],a[i] = a[i],a[c[i]]
+         end
+         table.insert(out, deepcopy(a))
+         c[i] = c[i]+1
+         i = 1
+      else
+        c[i] = 1
+         i = i+1
+      end
+   end
+   return out
+end
+function deepcopy(src)
+   local dst = {}
+   for k, v in pairs(src) do
+      if type(v) == "table" then
+         v = deepcopy(v)
+      end
+      dst[k] = v
+   end
+   return dst
+end
+
+function listcmp(a, b)
+   local ix = 1
+   while true do
+      if ix > #a and ix > #b then
+         return false
+      end
+      if ix <= #a and ix > #b then
+         return true
+      end
+      if ix > #a and ix <= #b then
+         return false
+      end
+      if a[ix] ~= b[ix] then
+         return a[ix] < b[ix]
+      end
+      ix = ix + 1
+   end
+end
+
+function nextpermutation(a)
+   local b = deepcopy(a)
+   table.sort(b)
+   local flag = false
+   local out = {}
+   local pp = permute(b)
+   table.sort(pp, listcmp)
+   for _, px in ipairs(pp) do
+      if #out == 0 then
+         out = px
+      end
+      if flag then
+         out = px
+      end
+      if recursive_compare(px, a) then
+         flag = true
+      end
+   end
+   return out
+end
+
+if recursive_compare(nextpermutation({1, 2, 3}), {1, 3, 2}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if recursive_compare(nextpermutation({2, 1, 3}), {2, 3, 1}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if recursive_compare(nextpermutation({3, 1, 2}), {3, 2, 1}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+
diff --git a/challenge-294/roger-bell-west/perl/ch-1.pl b/challenge-294/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..be1285a416
--- /dev/null
+++ b/challenge-294/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,40 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 3;
+
+is(consecutivesequence([10, 4, 20, 1, 3, 2]), 4, 'example 1');
+is(consecutivesequence([0, 6, 1, 8, 5, 2, 4, 3, 0, 7]), 9, 'example 2');
+is(consecutivesequence([10, 30, 20]), -1, 'example 3');
+
+use List::Util qw(max);
+
+sub consecutivesequence($a) {
+  my @b = sort {$::a <=> $::b} @{$a};
+  my $mxlen = 0;
+  my $here = 0;
+  while (1) {
+    foreach my $there (($here + 1) .. $#b) {
+      if ($b[$there] != $there - $here + $b[$here]) {
+        $mxlen = max($mxlen, $there - $here);
+        $here = $there;
+        last;
+      }
+      if ($there == $#b) {
+        $mxlen = max($mxlen, $there - $here + 1);
+        $here = $there;
+        last;
+      }
+    }
+    if ($here >= $#b) {
+      last;
+    }
+  }
+  if ($mxlen < 2) {
+    $mxlen = -1;
+  }
+  $mxlen;
+}
diff --git a/challenge-294/roger-bell-west/perl/ch-2.pl b/challenge-294/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..a78ea2fbc2
--- /dev/null
+++ b/challenge-294/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,35 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 3;
+
+is_deeply(nextpermutation([1, 2, 3]), [1, 3, 2], 'example 1');
+is_deeply(nextpermutation([2, 1, 3]), [2, 3, 1], 'example 2');
+is_deeply(nextpermutation([3, 1, 2]), [3, 2, 1], 'example 3');
+
+use Algorithm::Combinatorics qw(permutations);
+use Array::Compare;
+
+sub nextpermutation($a) {
+  my @b = sort {$::a <=> $::b} @{$a};
+  my $flag = 0;
+  my @out;
+  my $comp = Array::Compare->new;
+  my $ip = permutations(\@b);
+  while (my $px = $ip->next) {
+    if (scalar @out == 0) {
+      @out = @{$px};
+    }
+    if ($flag) {
+      @out = @{$px};
+      last;
+    }
+    if ($comp->compare($px, $a)) {
+      $flag = 1;
+    }
+  }
+  \@out;
+}
diff --git a/challenge-294/roger-bell-west/postscript/ch-1.ps b/challenge-294/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..67eeff8eb6
--- /dev/null
+++ b/challenge-294/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,161 @@
+%!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
+
+/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
+
+/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.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.cmp {
+    2 copy
+    lt {
+        pop pop -1
+    } {
+        gt {
+            1
+        } {
+            0
+        } ifelse
+    } 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
+
+/quicksort {
+    { quicksort.cmp } quicksort.with_comparator
+} 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
+
+
+% end included library code
+
+/consecutivesequence {
+    0 dict begin
+    quicksort /b exch def
+    /mxlen 0 def
+    /here 0 def
+    {
+        here 1 add 1 b length 1 sub {
+            /there exch def
+            b there get there here sub b here get add ne {
+                /mxlen mxlen there here sub max def
+                /here there def
+                exit
+            } if
+            there b length 1 sub eq {
+                /mxlen mxlen there here sub 1 add max def
+                /here there def
+                exit
+            } if
+        } for
+        here b length 1 sub ge {
+            exit
+        } if
+    } loop
+    mxlen 2 lt {
+        /mxlen -1 def
+    } if
+    mxlen
+    end
+} bind def
+
+(consecutivesequence) test.start
+[10 4 20 1 3 2] consecutivesequence 4 eq test
+[0 6 1 8 5 2 4 3 0 7] consecutivesequence 9 eq test
+[10 30 20] consecutivesequence -1 eq test
+test.end
diff --git a/challenge-294/roger-bell-west/postscript/ch-2.ps b/challenge-294/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..4a4ddaa659
--- /dev/null
+++ b/challenge-294/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,304 @@
+%!PS
+
+% begin included library code
+% see https://codeberg.org/Firedrake/postscript-libraries/
+/quicksort.with_keygen { % [ a c b ] { keygen } -> [ a b c ]
+    3 dict begin
+    /kg exch def
+    /arr exch def
+    /kl << arr {
+                dup kg
+            } forall >> def
+    arr {
+        exch kl exch get exch kl exch get quicksort.cmp
+    } quicksort.with_comparator
+} 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
+
+/keys { % dict -> array of dict keys
+    [ exch
+      {
+          pop
+      } forall
+    ]
+} 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.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} 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 {
+    { quicksort.cmp } quicksort.with_comparator
+} bind def
+
+/permute.swap {
+    /permute.bi exch def
+    /permute.ai exch def
+    permute.a permute.ai get
+    permute.a permute.bi get
+    permute.a exch permute.ai exch put
+    permute.a exch permute.bi exch put
+} bind def
+
+/test.end {
+    ( ) print
+    test.count 0 gt {
+        (Passed ) print