Rosetta Code/Tasks without examples

From Rosetta Code
Rosetta Code/Tasks without examples is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
A RosettaCode contributor is going on a long journey. To ease the boredom of a long flight he takes his favourite programming language manual and a list of RosettaCode tasks, but there's a catch: the tasks have to be description only and not include all the solutions already supplied by other programmers.

Task: Scrape for all the tasks. Traverse the links. Extract the text or html between a tag with a class of "infobox" and the beginning of the table with the id of "toc".

Perl 6[edit]

Works with: Rakudo version 2017.10
use HTTP::UserAgent;
use Gumbo;
my $ua =;
my $taskfile = './RC_tasks.html';
# Get list of Tasks
say "Updating Programming_Tasks list...";
my $page = "";
my $html = $ua.get($page).content;
my $xmldoc = parse-html($html, :TAG<div>, :id<mw-pages>);
my @tasks = parse-html($xmldoc[0].Str, :TAG<li>).Str.comb( /'/wiki/' <-["]>+ / )ยป.substr(6); #"
my $f = open("./RC_Programming_Tasks.txt", :w) or die "$!\n";
note "Writing Programming_Tasks file...";
$f.print( @tasks.join("\n") );
sleep .5;
for 'Programming_Tasks' -> $category
{ # Scrape info from each page.
note "Loading $category file...";
note "Retreiving tasks...";
my @entries = "./RC_{$category}.txt".IO.slurp.lines;
for @entries -> $title {
note $title;
# Get the raw page
my $html = $ua.get: "{$title}";
# Filter out the actual task description
$html.content ~~ m|'<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><div'
.+? 'using any language you may know.</div>' (.+?) '<div id="toc"'|;
my $task = cleanup $0.Str;
# save to a file
my $fh = $ :a;
$fh.put: "<hr>\n $title\n<hr>\n$task";
sleep 3; # Don't pound the server
sub cleanup ( $string ) {
$string.subst( /^.+ '</div>'/, '' )
Abridged sample output:


There are 100 doors in a row that are all initially closed.

You make 100 <a href="/wiki/Rosetta_Code:Multiple_passes" title="Rosetta Code:Multiple passes">passes</a> by the doors.

The first time through, visit every door and  toggle  the door  (if the door is closed,  open it;   if it is open,  close it).

The second time, only visit every 2nd door   (door #2, #4, #6, ...),   and toggle it.

The third time, visit every 3rd door   (door #3, #6, #9, ...), etc,   until you only visit the 100th door.


Answer the question:   what state are the doors in after the last pass?   Which are open, which are closed?

<a href="/wiki/Rosetta_Code:Extra_credit" title="Rosetta Code:Extra credit">Alternate</a>: As noted in this page's   <a href="/wiki/Talk:100_doors" title="Talk:100 doors">discussion page</a>,   the only doors that remain open are those whose numbers are perfect squares.

Opening only those doors is an   <a href="/wiki/Rosetta_Code:Optimization" title="Rosetta Code:Optimization">optimization</a>   that may also be expressed;

however, as should be obvious, this defeats the intent of comparing implementations across programming languages.



Implement the <a href="" class="extiw" title="wp:15 puzzle">Fifteen Puzzle Game</a>.

Related Task
  • <a href="/wiki/15_puzzle_solver" title="15 puzzle solver">15 Puzzle Solver</a>


Your task is to write a program that finds a solution in the fewest single moves (no multimoves) possible to a random <a href="" class="extiw" title="wp:15 puzzle">Fifteen Puzzle Game</a>.
For this task you will be using the following puzzle:

15 14  1  6
 9 11  4 12
 0 10  7  3
13  8  5  2

 1  2  3  4
 5  6  7  8
 9 10 11 12
13 14 15  0

The output must show the moves' directions, like so: left, left, left, down, right... and so on.
There are 2 solutions with 52 moves:
finding either one, or both is an acceptable result.
see: <a rel="nofollow" class="external text" href="">Pretty Print of Optimal Solution</a>

Extra credit.

Solve the following problem:

  0 12  9 13
 15 11 10 14
  3  7  2  5
  4  8  6  1

Related Task
  • <a href="/wiki/15_Puzzle_Game" title="15 Puzzle Game">15 puzzle game</a>

...and so on...


Uses Internet Explorer (v9 and above) to traverse the DOM in the list page and subsequent task pages. Echoes title and href to the console. Outputs files containing html.

Could output text by retrieving innerText instead of innerHTML in Slurp().

Option Explicit
Dim oIE : Set oIE = CreateObject("InternetExplorer.Application")
Dim oFSO : Set oFSO = CreateObject("Scripting.FileSystemObject")
Dim oRE : Set oRE = New RegExp
oRE.Pattern = "class=[" & Chr(34) & "'](.*?)[" & Chr(34) & "']"
oRE.IgnoreCase = True
oIE.Navigate ""
While oIE.Busy
WScript.Sleep 100
Dim oDoc : Set oDoc = oIE.Document
Dim oDict : Set oDict = CreateObject("Scripting.Dictionary")
' build a dictionary of anchors
Dim oAnchor
Dim oAnchors : Set oAnchors = oDoc.getElementById("mw-pages").getElementsByTagName("a")
For Each oAnchor In oAnchors
oDict.Add oAnchor.innerText, oAnchor.href
'traverse the dictionary of anchors
Dim aKeys : aKeys = oDict.Keys()
Dim aKey
For Each aKey In aKeys
Slurp aKey, oDict(aKey)
Function Slurp(sTitle, sHref)
WScript.Echo sTitle, sHref
oIE.Navigate sHref
While oIE.Busy
WScript.Sleep 100
Dim oDoc : Set oDoc = oIE.Document
Dim oStart : Set oStart = oDoc.getElementsByClassName("infobox")(0)
Dim oCursor : Set oCursor = oStart
Dim sDescription : sDescription = vbNullString
Dim oThere
Dim iErr
Do While oCursor.tagName <> "TABLE" And <> "toc"
Set oThere = oCursor
sDescription = sDescription & oThere.innerHTML & vbNewLine
On Error Resume Next
Set oCursor = oCursor.nextElementSibling
iErr = Err.Number
On Error Goto 0
If iErr <> 0 Then
Exit Do
End If
dim sTitle2
sTitle2 = Replace(sTitle,"/","_")
sTitle2 = Replace(sTitle2,Chr(34),"'")
sTitle2 = Replace(sTitle2,"*",".")
Dim oHandle : Set oHandle = oFSO.CreateTextFile(sTitle2 & ".htm", True, True)
oHandle.Write "<a href='" & sHref & "'>" & sTitle & "</a><br><br>"
oHandle.Write sDescription
End Function