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#!/usr/bin/perl
# https://theweeklychallenge.org/blog/perl-weekly-challenge-200/#TASK2
#
# A seven segment display is an electronic component, usually used to display
# digits. The segments are labeled 'a' through 'g' as shown:
#
# a
# -------
# f | | b
# | g |
# -------
# e | | c
# | d |
# -------
#
# The encoding of each digit can thus be represented compactly as a truth table:
## my @truth = qw<abcdef bc abdeg abcdg bcfg acdfg acdefg abc abcdefg abcfg>;
# For example, $truth[1] = ‘bc’. The digit 1 would have segments ‘b’ and ‘c’ enabled.
#
# Write a program that accepts any decimal number and draws that number as a
# horizontal sequence of ASCII seven segment displays, similar to the
# following:
#
# ------- ------- -------
# | | | | |
# | | | | |
# -------
# | | | | |
# | | | | |
# ------- ------- -------
#
# To qualify as a seven segment display, each segment must be drawn (or not drawn) according to your @truth table.
#
# The number "200" was of course chosen to celebrate our 200th week!
##############################################
##
## discussion
##
##############################################
##
## basically we need to find a way to print one digit after another
## since terminal output is a bit special, we basically need to
## build that number as a series of strings one after another
## then we can append the next digit as a series of strings to the
## existing ones
## at the end we can print everything
##
## in order to print longer numbers more nicely, we can als wrap long
## lines just before we reach the end of the terminal width
use strict;
use warnings;
use feature 'say';
my $dimensions = `stty size`;
chomp($dimensions);
my ($rows, $columns) = split /\s+/, $dimensions;
my $MAX_LEN = $columns // 80;
$MAX_LEN -= 9; # make sure the last digit fits completely on the line
die "Terminal too small, try a bigger terminal" if $MAX_LEN < 10;
my @examples = (200, 1, 17, 12425, "123423509876823456567124");
my @truth = qw<abcdef bc abdeg abcdg bcfg acdfg acdefg abc abcdefg abcfg>;
foreach my $number (@examples) {
print_number($number);
}
# print a number
sub print_number {
my $number = shift;
# split the number into individual digits
my @digits = split //, $number;
my @print;
foreach my $digit (@digits) {
# get the truth for the given digit
my $truth = $truth[$digit];
# split the truth into a list of segments that are to be set
my @set_segments = split //, $truth;
# but this list of segments into a hash table for easier access
my %set = map { $_ => 1, } @set_segments;
# now for each possible segment, check whether it is set or not
# and append the required output to the corresponding element of
# the output array
if($set{"a"}) {
$print[0] .= " ------- ";
} else {
$print[0] .= " ";
}
if($set{"f"}) {
$print[1] .= " |";
$print[2] .= " |";
} else {
$print[1] .= " ";
$print[2] .= " ";
}
if($set{"b"}) {
$print[1] .= " | ";
$print[2] .= " | ";
} else {
$print[1] .= " ";
$print[2] .= " ";
}
if($set{"g"}) {
$print[3] .= " ------- ";
} else {
$print[3] .= " ";
}
if($set{"e"}) {
$print[4] .= " |";
$print[5] .= " |";
} else {
$print[4] .= " ";
$print[5] .= " ";
}
if($set{"c"}) {
$print[4] .= " | ";
$print[5] .= " | ";
} else {
$print[4] .= " ";
$print[5] .= " ";
}
if($set{"d"}) {
$print[6] .= " ------- ";
} else {
$print[6] .= " ";
}
# if we hit the terminal width, output
# the digits so far and empty the array
# again for the remaining digits
if(length($print[0]) > $MAX_LEN) {
foreach my $line (@print) {
say $line;
}
@print = ();
}
}
# print the digits
foreach my $line (@print) {
say $line;
}
}
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