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#!/usr/bin/env raku
use v6.d;
use WWW;
unit sub MAIN (
Str $url, #= url for Algot's crossword
Str :$dict = "/usr/share/dict/words", #= dictionary file
Bool :v($verbose), #= increase verbosity
);
my List @directions[4] = (
# $y, $x
( +1, +0 ), # bottom
( -1, +0 ), # top
( +0, +1 ), # left
( +0, -1 ), # right
);
# my List @puzzle = (
# <n a t k>,
# <i m e c>,
# <a r d e>,
# <t e c h>
# );
# my List @gray-squares = (3, 0), (2, 0); # $y, $x
my @puzzle;
my @gray-squares;
my Str $toot_url;
if $url.match("web/statuses") -> $match {
$toot_url = $match.replace-with("api/v1/statuses");
} else {
$toot_url = "https://mastodon.art/api/v1/statuses/" ~ $url.split("/")[*-1];
}
say "Fetching: $toot_url" if $verbose;
if (jget($toot_url)<media_attachments>[0]<description> ~~
# This regex gets the puzzle in $match.
/ [[(\w [\*]?) \s*] ** 4] ** 4 $/) -> $match {
for 0 .. 3 -> $y {
for 0 .. 3 -> $x {
with $match[0][($y * 4) + $x].Str.lc -> $char {
if $char.ends-with("*") {
@puzzle[$y][$x] = $char.comb[0];
push @gray-squares, [$y, $x];
} else {
@puzzle[$y][$x] = $char;
}
}
}
}
}
if $verbose {
say "Gray squares: ", @gray-squares;
say "Puzzle";
" $_".say for @puzzle;
}
word: for $dict.IO.lines -> $word {
next word unless $word.chars >= 7;
start-pos: for @gray-squares -> $pos {
next start-pos unless $word.starts-with(
@puzzle[$pos[0]][$pos[1]]
);
next word unless $word.comb ⊆ @puzzle[*;*];
# Print the word if the search is successful.
say $word if word-search(@puzzle, $pos[0], $pos[1], $word);
}
}
# word-search performs a Depth-First search on @puzzle.
sub word-search (
@puzzle, Int $y, Int $x,
# $count will keep the count of character's of $word present in
# the puzzle.
Str $word, Int $count = 1,
@visited? is copy
--> Bool
) {
return True if $count == $word.chars;
# For each neighbor, we perform a Depth-First search to find the
# word.
neighbor: for neighbors(@puzzle, $y, $x).List -> $pos {
next neighbor if @visited[$pos[0]][$pos[1]];
if @puzzle[$pos[0]][$pos[1]] eq $word.comb[$count] {
# Here we're marking this position as True. This approach
# might cause us to miss possible solutions. If the puzzle
# is like so:
#
# a b e
# c a f
#
# And the word we're looking for is "cabefa". Then let's
# say that we go through the other 'a' first (bottom-mid
# 'a') & at this point it would be marked as True but the
# search would fail (correctly so).
#
# And after that failure we move to next neighbor which is
# top-left 'a'. The search goes on until we reach 'f' &
# get the list of f's neighbors which would return 'e' &
# bottom-mid 'a'. Now 'e' would be discarded because it
# was marked as visited but 'a' also has been marked as
# visited & it too would be discarded.
#
# This would cause us to miss solutions. So we just make
# it False again if the word wasn't found with this
# neighbor. After making it False, we move on to the next
# neighbor.
@visited[$pos[0]][$pos[1]] = True;
if word-search(
@puzzle, $pos[0], $pos[1],
$word, $count + 1,
@visited
) {
return True;
} else {
@visited[$pos[0]][$pos[1]] = False;
next neighbor;
}
}
}
return False;
}
# neighbors returns the neighbors of given index. Neighbors are cached
# in @neighbors array. This way we don't have to compute them
# everytime neighbors subroutine is called for the same position.
sub neighbors (
@puzzle, Int $y, Int $x --> List
) {
state Array @neighbors;
if @puzzle[$y][$x] {
unless @neighbors[$y][$x] {
my Int $pos-x;
my Int $pos-y;
DIRECTION: for @directions -> $direction {
$pos-y = $y + $direction[0];
$pos-x = $x + $direction[1];
next DIRECTION unless @puzzle[$pos-y][$pos-x];
push @neighbors[$y][$x], [$pos-y, $pos-x];
}
}
} else {
@neighbors[$y][$x] = [];
}
return @neighbors[$y][$x];
}
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