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#!/usr/bin/env perl
# -*- Mode: cperl; cperl-indent-level:4 tab-width: 8; indent-tabs-mode: nil -*-
# -*- coding: utf-8 -*-
# tested with:
# echo "[000111][111111][001001][001111][001111] | sbcl --script ch-2.lsp
# [000111]
# [111111]
# [001001]
# [001111]
# [001111]
# modified from ch-084/ch-2.pl
use strict; use warnings;
use v5.26;
use Class::Struct;
struct PointInMat => [ row => '$', col => '$' ];
struct HLineInMat => [ row => '$', begin => '$', end => '$' ];
struct RectInMat => [ row_NW => '$', col_NW => '$',
row_SE => '$', col_SE => '$' ];
struct RunAndShow => [ Run => '$', Show => '$' ];
struct ShowDetails => [ name => '$', attrs => '@' ];
sub rectArea ($) {
my $rect = shift;
($rect->row_SE - $rect->row_NW + 1)
*
($rect->col_SE - $rect->col_NW + 1)
}
sub readContents {
local $/ = ''; # slurp
my $contents = <STDIN> // '';
$contents
}
# return as an ArrayRef of ArrayRef of PointInMat (grouped by row number)
sub getPointsAtEachRows ($) {
my $raw_string = shift;
my @lines = split( /\n|]\s*/, $raw_string );
[ map {
my ( $r, $c ) = ( $_, 0 );
[ map {
if ( $_ eq '1' ) {
PointInMat->new( row => $r, col => $c++ );
} elsif ( $_ eq '0' ) {
++$c; ()
} else {
()
}
} (split "", $lines[$_]) # charaters
] # group by row
} 0 .. $#lines ]; # return as ArrayRef
}
sub showSomethingInGroup ($$$) {
my ( $listOflist_ref, $spec, $flattening, $nth ) = ( @_[0..2], 1 );
my @list;
if ( $flattening // 1 ) {
@list = map { @$_ } @$listOflist_ref; # flatten
}
else {
@list = @$listOflist_ref;
}
my $listLen = scalar @list;
my $ww = length $listLen; # (w)ord (w)idth: for printf()
say "$listLen ".($spec->name)."(s) found:";
for my $sth (@list) {
printf("%0*d", $ww, $nth++);
say ": (".join(", ", map { "$_:".($sth->$_()) } @{$spec->attrs} ).")";
}
say "";
}
sub showPoints ($) {
@_ = ( $_[0], # data (ArrayRef)
ShowDetails->new( name => 'points',
attrs => [qw(row col)] ),
1 # flattening? yes
);
goto &showSomethingInGroup
}
# return as an ArrayRef of ArrayRef of HLineInMat (grouped by row)
sub getHorizLinesFromPoints ($) {
my $pts_at_all_rows = shift;
[ map {
my $pts_at_the_same_row = $_;
my $prev = shift @$pts_at_the_same_row;
my @line_so_far = ($prev->col);
my $row = $prev->row;
push @$pts_at_the_same_row,
PointInMat->new( row => $row, # add dummy
col => $$pts_at_the_same_row[-1]->col + 2 );
my @hline;
for my $curr ( @$pts_at_the_same_row ) {
if ( $curr->col - $prev->col == 1 ) {
push @line_so_far, $curr->col
}
elsif ( scalar @line_so_far > 0 ) {
push @hline,
HLineInMat->new( row => $row,
begin => $line_so_far[0],
end => $line_so_far[-1] );
@line_so_far = ( $curr->col );
}
$prev = $curr;
}
# return all possible combinations of sub lines
# single points are inclusive
my @sub_hline;
while (@hline) {
my $sub_hline = shift @hline;
push @sub_hline, $sub_hline; # itself
my @range = $sub_hline->begin .. $sub_hline->end;
for my $nsel ( reverse 1 .. $#range ) { # from larger to smaller
for my $offset ( 0.. scalar @range - $nsel ) {
push @sub_hline,
HLineInMat->new( row => $sub_hline->row,
begin => $range[$offset],
end => $range[$offset+$nsel-1] )
}
}
}
[ @sub_hline ];
} @$pts_at_all_rows ]
}
sub showHorizLines ($) {
@_ = ( $_[0],
ShowDetails->new( name => 'horiz line(point inclusive)',
attrs => [qw(row begin end)] ),
1 # flattening? yes
);
goto &showSomethingInGroup
}
# take ArrayRef of ArrayRef of HLine
sub findLargestRectanglesFromHorizLines ($) {
my @hlines_grouped_by_row = @{$_[0]}; # copy
my @largestRectangles = ();
my $largestArea = 0;
# reducing rows: 1,2,3,4 -> 2,3,4 -> 3,4 -> 4
for ( my $base = 0 ; scalar @hlines_grouped_by_row > 0;
shift @hlines_grouped_by_row, ++$base ) {
# initial intersection is same as first row
my %intersects = map {
$_->begin."~".$_->end => 1 # "begin~end" as a key
} @{$hlines_grouped_by_row[0]};
for my $candi_row (@hlines_grouped_by_row) {
my %new_inters = ();
last if scalar %intersects == 0; # no need to go further
for my $hline (@$candi_row) {
my $key = $hline->begin."~".$hline->end;
if ( exists $intersects{$key} ) {
$new_inters{$key} = 1;
my $rect = RectInMat->new(
row_NW => $base,
row_SE => $hline->row,
col_NW => $hline->begin,
col_SE => $hline->end );
# check largest
my $new_area = rectArea( $rect );
if ( $largestArea < $new_area ) {
$largestArea = $new_area;
@largestRectangles = ( $rect );
}
elsif ( $largestArea == $new_area ) {
push @largestRectangles, $rect;
}
}
else {
}
}
%intersects = %new_inters;
}
}
[ @largestRectangles ]
}
# return as an ArrayRef of PointInMat
sub showRects ($) {
@_ = ( $_[0],
ShowDetails->new( name => 'rectangles',
attrs => [ qw(row_NW col_NW row_SE col_SE) ] ),
0 # flattening? no
);
goto &showSomethingInGroup
}
my @solutionComposed =
(
# pairs of function, logger in top -> bottom in the same order of exe.
RunAndShow->new( Run => \&readContents, Show => sub { say @_ } ),
# ==>
RunAndShow->new( Run => \&getPointsAtEachRows,
Show => \&showPoints ),
# ==>
RunAndShow->new( Run => \&getHorizLinesFromPoints,
Show => \&showHorizLines ),
# ==>
RunAndShow->new( Run => \&findLargestRectanglesFromHorizLines,
Show => \&showRects ),
);
our $debug = 0;
my $ball;
my @progress = map {
$ball = $_->Run->($ball);
if ( $debug ) { $_->Show->($ball); }
$ball
} @solutionComposed;
say "Output: ";
for my $rect (@{$progress[-1]}) {
say "At (r:".$rect->row_NW.", c:".$rect->col_NW.")";
say join(" ", (1) x ($rect->col_SE - $rect->col_NW + 1))
for (0 .. $rect->row_SE - $rect->row_NW);
}
|
