Rosetta Code/Tasks without examples
A RosettaCode contributor is going on a long journey.
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.
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 http://rosettacode.org/wiki/Category:Programming_Tasks 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".
D
<lang d>import std.algorithm; import std.net.curl; import std.range; import std.regex; import std.stdio; import std.string;
void process(string base, string task) {
auto re2 = ctRegex!`</?[^>]*>`;
auto page = base ~ task; auto content = get(page);
string prefix = `using any language you may know.`;
auto beg = content.indexOf(prefix); auto end = content.indexOf(`<div id="toc"`, beg); auto snippet = content[beg + prefix.length .. end]; writeln(replaceAll(snippet, re2, ``));
writeln("#####################################################");
}
void main() {
auto pattern = ctRegex!`
- Output:
There are 100 doors in a row that are all initially closed. You make 100 passes 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. Task Answer the question: what state are the doors in after the last pass? Which are open, which are closed? Alternate: As noted in this page's discussion page, the only doors that remain open are those whose numbers are perfect squares. Opening only those doors is an optimization that may also be expressed; however, as should be obvious, this defeats the intent of comparing implementations across programming languages. ##################################################### The Problem 100 prisoners are individually numbered 1 to 100 A room having a cupboard of 100 opaque drawers numbered 1 to 100, that cannot be seen from outside. Cards numbered 1 to 100 are placed randomly, one to a drawer, and the drawers all closed; at the start. Prisoners start outside the room They can decide some strategy before any enter the room. Prisoners enter the room one by one, can open a drawer, inspect the card number in the drawer, then close the drawer. A prisoner can open no more than 50 drawers. A prisoner tries to find his own number. A prisoner finding his own number is then held apart from the others. If all 100 prisoners find their own numbers then they will all be pardoned. If any don't then all sentences stand. The task Simulate several thousand instances of the game where the prisoners randomly open drawers Simulate several thousand instances of the game where the prisoners use the optimal strategy mentioned in the Wikipedia article, of: First opening the drawer whose outside number is his prisoner number. If the card within has his number then he succeeds otherwise he opens the drawer with the same number as that of the revealed card. (until he opens his maximum). Show and compare the computed probabilities of success for the two strategies, here, on this page. References The unbelievable solution to the 100 prisoner puzzle standupmaths (Video). wp:100 prisoners problem 100 Prisoners Escape Puzzle DataGenetics. Random permutation statistics#One hundred prisoners on Wikipedia. ##################################################### Task Implement the Fifteen Puzzle Game. The 15-puzzle is also known as: Fifteen Puzzle Gem Puzzle Boss Puzzle Game of Fifteen Mystic Square 14-15 Puzzle and many others. Related Tasks 15 Puzzle Solver 16 Puzzle Game #####################################################
Go
<lang go>package main
import (
"fmt" "html" "io/ioutil" "net/http" "regexp" "strings" "time"
)
func main() {
ex := ` ex2 := `</?[^>]*>` // to remove all tags including links
re = regexp.MustCompile(ex)
re2 := regexp.MustCompile(ex2)
for i, task := range tasks {
page = base + task
resp, _ = http.Get(page)
body, _ = ioutil.ReadAll(resp.Body)
match := re.FindStringSubmatch(string(body))
resp.Body.Close()
text := html.UnescapeString(re2.ReplaceAllLiteralString(match[1], ""))
fmt.Println(strings.Replace(task, "_", " ", -1), "\n", text)
if i == limit-1 {
break
}
time.Sleep(5 * time.Second) // wait 5 seconds before processing next task
}
}</lang>
- Output:
Text rather than HTML:
100 doors There are 100 doors in a row that are all initially closed. You make 100 passes 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. Task Answer the question: what state are the doors in after the last pass? Which are open, which are closed? Alternate: As noted in this page's discussion page, the only doors that remain open are those whose numbers are perfect squares. Opening only those doors is an optimization that may also be expressed; however, as should be obvious, this defeats the intent of comparing implementations across programming languages. 15 Puzzle Game Task Implement the Fifteen Puzzle Game. The 15-puzzle is also known as: Fifteen Puzzle Gem Puzzle Boss Puzzle Game of Fifteen Mystic Square 14-15 Puzzle and many others. Related Tasks 15 Puzzle Solver 16 Puzzle Game 15 puzzle solver Your task is to write a program that finds a solution in the fewest moves possible single moves to a random Fifteen Puzzle Game. 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 Solution: 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 two solutions, of fifty-two moves: rrrulddluuuldrurdddrullulurrrddldluurddlulurruldrdrd rrruldluuldrurdddluulurrrdlddruldluurddlulurruldrrdd see: Pretty Print of Optimal Solution Finding either one, or both is an acceptable result. Extra credit. Solve the following problem: 0 12 9 13 15 11 10 14 3 7 2 5 4 8 6 1 Related Task 15 puzzle game A* search algorithm
Java
<lang Java>import java.io.IOException; import java.net.URI; import java.net.URISyntaxException; import java.net.http.HttpClient; import java.net.http.HttpRequest; import java.net.http.HttpResponse; import java.time.Duration; import java.util.ArrayList; import java.util.regex.Pattern;
public class TasksWithoutExamples {
private static String readPage(HttpClient client, URI uri) throws IOException, InterruptedException {
var request = HttpRequest.newBuilder()
.GET()
.uri(uri)
.timeout(Duration.ofSeconds(5))
.setHeader("accept", "text/html")
.build();
var response = client.send(request, HttpResponse.BodyHandlers.ofString());
return response.body();
}
private static void process(HttpClient client, String base, String task) {
try {
var re = Pattern.compile(".*using any language you may know.(.*?)<div id=\"toc\".*", Pattern.DOTALL + Pattern.MULTILINE);
var re2 = Pattern.compile("</?[^>]*>");
var page = base + task;
String body = readPage(client, new URI(page));
var matcher = re.matcher(body);
if (matcher.matches()) {
var group = matcher.group(1);
var m2 = re2.matcher(group);
var text = m2.replaceAll("");
System.out.println(text);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws URISyntaxException, IOException, InterruptedException {
var re = Pattern.compile("Julia
<lang julia>using HTTP
function gettaskdescriptions(numtoprint = 3)
page = "http://rosettacode.org/wiki/Category:Programming_Tasks" body = String(HTTP.get(page).body)tasks = [m.captures[1] for m in eachmatch(r"
m != nothing && println(replace(m.captures[1], r"<[^>]*>"s => ""), "\n", "="^60, "\n")
i >= numtoprint && break
sleep(rand(3:7)) # wait 5 +/- 2 seconds before processing next task
end
end
gettaskdescriptions() </lang>
Kotlin
<lang scala>import java.net.URI import java.net.http.HttpClient import java.net.http.HttpRequest import java.net.http.HttpResponse import java.time.Duration import java.util.regex.Pattern
fun readPage(client: HttpClient, uri: URI): String {
val request = HttpRequest.newBuilder()
.GET()
.uri(uri)
.timeout(Duration.ofSeconds(5))
.setHeader("accept", "text/html")
.build()
val response = client.send(request, HttpResponse.BodyHandlers.ofString()) return response.body()
}
fun main() {
var re = Pattern.compile(" val re2 = Pattern.compile("</?[^>]*>")
for (task in tasks.stream().limit(limit)) {
val page = base + task
body = readPage(client, URI(page))
matcher = re.matcher(body)
if (matcher.matches()) {
val group = matcher.group(1)
val m2 = re2.matcher(group)
val text = m2.replaceAll("")
println(text)
}
}
}</lang>
Nim
<lang Nim>import htmlparser, httpclient, os, re, strutils, xmltree
let re1 = re("""- Find tasks.
for i, task in tasks:
var matches: array[2, string]
let page = Base & task
body = client.getContent(page)
if body.find(re2, matches) < 0:
raise newException(ValueError, "unable to find pattern in page.")
let xmlnode = matches[0].parseHtml() # Build an XML tree from the HTML.
echo task.replace('_', ' ')
echo xmlnode.innerText() # Echo the tree as text.
if i == Limit - 1: break
os.sleep(5000) # Wait 5 seconds before processing next task.</lang>
- Output:
100 doors There are 100 doors in a row that are all initially closed. You make 100 passes 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. Task Answer the question: what state are the doors in after the last pass? Which are open, which are closed? Alternate: As noted in this page's discussion page, the only doors that remain open are those whose numbers are perfect squares. Opening only those doors is an optimization that may also be expressed; however, as should be obvious, this defeats the intent of comparing implementations across programming languages. 100 prisoners The Problem 100 prisoners are individually numbered 1 to 100 A room having a cupboard of 100 opaque drawers numbered 1 to 100, that cannot be seen from outside. Cards numbered 1 to 100 are placed randomly, one to a drawer, and the drawers all closed; at the start. Prisoners start outside the room They can decide some strategy before any enter the room. Prisoners enter the room one by one, can open a drawer, inspect the card number in the drawer, then close the drawer. A prisoner can open no more than 50 drawers. A prisoner tries to find his own number. A prisoner finding his own number is then held apart from the others. If all 100 prisoners find their own numbers then they will all be pardoned. If any don't then all sentences stand. The task Simulate several thousand instances of the game where the prisoners randomly open drawers Simulate several thousand instances of the game where the prisoners use the optimal strategy mentioned in the Wikipedia article, of: First opening the drawer whose outside number is his prisoner number. If the card within has his number then he succeeds otherwise he opens the drawer with the same number as that of the revealed card. (until he opens his maximum). Show and compare the computed probabilities of success for the two strategies, here, on this page. References The unbelievable solution to the 100 prisoner puzzle standupmaths (Video). wp:100 prisoners problem 100 Prisoners Escape Puzzle DataGenetics. Random permutation statistics#One hundred prisoners on Wikipedia. 15 puzzle game Task Implement the Fifteen Puzzle Game. The 15-puzzle is also known as: Fifteen Puzzle Gem Puzzle Boss Puzzle Game of Fifteen Mystic Square 14-15 Puzzle and some others. Related Tasks 15 Puzzle Solver 16 Puzzle Game
Perl
Slice and dice the HTML. Output is as for the other examples. <lang perl>use strict; use warnings;
use LWP::UserAgent; my $ua = LWP::UserAgent->new;
- get list of task titles
my $html = $ua->request( HTTP::Request->new( GET => 'http://rosettacode.org/wiki/Category:Programming_Tasks'))->content;
my @tasks = $html =~ m#- download tasks, and extract task descriptions
print "$title\n$task_at_hand\n\n"; sleep 10; # so you have time to read each task...
}</lang>
Phix
Since downloading all the pages can be very slow, this uses a cache. Limiting by "Phix" fairly obviously speeds it up tenfold :-)
Output similar to zkl, I assume the first four constants are self-explanatory.
<lang Phix>-- demo\rosetta\Tasks_without_examples.exw constant output_html = true,
include_drafts = true,
summary = false,
notlang = "Phix" -- "" for all
include builtins\timedate.e integer refresh_cache = timedelta(days:=30) -- 0 for always
include builtins\libcurl.e atom curl = NULL atom pErrorBuffer
function write_callback(atom pData, integer size, integer nmemb, integer fn)
integer bytes_written = size * nmemb
puts(fn,peek({pData,bytes_written}))
return bytes_written
end function constant write_cb = call_back({'+', routine_id("write_callback")})
function open_download(string filename, url)
bool refetch = true
if get_file_type("rc_cache")!=FILETYPE_DIRECTORY then
if not create_directory("rc_cache") then
crash("cannot create rc_cache directory")
end if
end if
filename = join_path({"rc_cache",filename})
if file_exists(filename) then
-- use existing file if <= refresh_cache (30+ days) old
sequence last_mod = get_file_date(filename) -- (0.8.1+)
atom delta = timedate_diff(last_mod,date())
refetch = (delta>refresh_cache)
else
string directory = get_file_path(filename)
if get_file_type(directory)!=FILETYPE_DIRECTORY then
if not create_directory(directory,make_parent:=true) then
crash("cannot create %s directory",{directory})
end if
end if
end if
if refetch then
printf(1,"Downloading %s...\n",{filename})
if curl=NULL then
curl_global_init()
curl = curl_easy_init()
pErrorBuffer = allocate(CURL_ERROR_SIZE)
curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, pErrorBuffer)
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb)
end if
url = substitute(url,"%3A",":")
url = substitute(url,"%2A","*")
curl_easy_setopt(curl, CURLOPT_URL, url)
integer fn = open(filename,"wb")
if fn=-1 then ?9/0 end if
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fn)
CURLcode res = curl_easy_perform(curl)
if res!=CURLE_OK then
string error = sprintf("%d",res)
if res=CURLE_COULDNT_RESOLVE_HOST then
error &= " [CURLE_COULDNT_RESOLVE_HOST]"
end if
printf(1, "Error %s downloading file\n", error)
{} = wait_key()
abort(0)
end if
close(fn)
refresh_cache += timedelta(days:=1) -- did I mention it is slow?
end if
return get_text(filename)
end function
function open_category(string filename)
return open_download(filename&".htm","http://rosettacode.org/wiki/Category:"&filename)
end function
function dewiki(string s)
sequence tasks = {}
integer start = 1, finish = match(` integer finish = match(`<div id="toc"`,contents,start)-1
-- ... but draft tasks with too few languages have no toc:
if finish=-1 then finish = match(`