RogerBW's Blog

The Weekly Challenge 265: The Appearance of Completion 21 April 2024

I’ve been doing the Weekly Challenges. The latest involved hunting integers and filtering words. (Note that this ends today.)

Task 1: 33% Appearance

You are given an array of integers, @ints.

Write a script to find an integer in the given array that appeared 33% or more. If more than one found, return the smallest. If none found then return undef.

So I'll count the occurrences, and compare with a threshold value. Python:

def thirtythreepercentappearance(a):

Count occurrences.

  m = defaultdict(lambda: 0);
  for n in a:
    m[n] += 1

Work out the threshold.

  threshold = floor(len(a) * 33 / 100)

If it wasn't an exact integer value, nudge it up by 1. (So 100 yields a threshold off 33, but 4 yields 2.)

  if floor(threshold * 100 / 33) != len(a):
    threshold += 1

Get the list of qualifying keys.

  s = [k for k in m.keys() if m[k] >= threshold]

And return either the minimum of them, or a flag value. (In Rust I can use an Option.)

  if len(s) > 0:
    return min(s)
  else:
    return -1

Task 2: Completing Word

You are given a string, $str containing alphnumeric characters and array of strings (alphabetic characters only), @str.

Write a script to find the shortest completing word. If none found return empty string.

A completing word is a word that contains all the letters in the given string, ignoring space and number. If a letter appeared more than once in the given string then it must appear the same number or more in the word.

Once more it's the hash as count of occurrences, this time also filtering for relevant characters. Perl:

Build a hash from a string.

sub str2hash($a) {
  my %m;
  foreach my $c (split '', $a) {
    if ($c =~ /[[:alpha:]]/) {
      $m{lc($c)}++;
    }
  }
  return \%m;
}

sub completingword($a, $cw) {

Make the reference hash.

  my $ah = str2hash($a);
  my @out;

For each possible completing word, make its hash.

  foreach my $t (@{$cw}) {
    my $valid = 1;
    my $th = str2hash($t);

Fiddly bit to reset the hash access counter, since we'll be using each multiple times on the same hash.

    keys %{$ah};
    while (my ($k, $v) = each %{$ah}) {

If the cw hash doesn't have an entry that's in the main word hash,

      unless (exists $th->{$k}) {
        $valid = 0;
        last;
      }

or it doesn't have enough letters, bail out.

      if ($th->{$k} < $v) {
        $valid = 0;
        last;
      }
    }

Otherwise this is a valid completing word.

    if ($valid) {
      push @out, $t;
    }
  }

No completions? Return empty string.

  unless (@out) {
    return "";
  }

Otherwise return the shortest.

  return (sort {length($::a) <=> length($::b)} @out)[0];
}

Full code on github.

Add A Comment

Your Name
Your Email
Your Comment

Your submission will be ignored if any field is left blank, but your email address will not be displayed. Comments will be processed through markdown.

Search
Archive
Tags 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s 2010s 3d printing action advent of code aeronautics aikakirja anecdote animation anime army astronomy audio audio tech aviation base commerce battletech beer boardgaming book of the week bookmonth chain of command children chris chronicle church of no redeeming virtues cold war comedy computing contemporary cornish smuggler cosmic encounter coup covid-19 crime crystal cthulhu eternal cycling dead of winter doctor who documentary drama driving drone ecchi economics en garde espionage essen 2015 essen 2016 essen 2017 essen 2018 essen 2019 essen 2022 essen 2023 existential risk falklands war fandom fanfic fantasy feminism film firefly first world war flash point flight simulation food garmin drive gazebo genesys geocaching geodata gin gkp gurps gurps 101 gus harpoon historical history horror hugo 2014 hugo 2015 hugo 2016 hugo 2017 hugo 2018 hugo 2019 hugo 2020 hugo 2021 hugo 2022 hugo 2023 hugo 2024 hugo-nebula reread in brief avoid instrumented life javascript julian simpson julie enfield kickstarter kotlin learn to play leaving earth linux liquor lovecraftiana lua mecha men with beards mpd museum music mystery naval noir non-fiction one for the brow opera parody paul temple perl perl weekly challenge photography podcast politics postscript powers prediction privacy project woolsack pyracantha python quantum rail raku ranting raspberry pi reading reading boardgames social real life restaurant reviews romance rpg a day rpgs ruby rust scala science fiction scythe second world war security shipwreck simutrans smartphone south atlantic war squaddies stationery steampunk stuarts suburbia superheroes suspense television the resistance the weekly challenge thirsty meeples thriller tin soldier torg toys trailers travel type 26 type 31 type 45 vietnam war war wargaming weather wives and sweethearts writing about writing x-wing young adult
Special All book reviews, All film reviews
Produced by aikakirja v0.1