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|
#!perl
###############################################################################
=comment
Perl Weekly Challenge 194
=========================
TASK #1
-------
*Digital Clock*
Submitted by: Mohammad S Anwar
You are given time in the format hh:mm with one missing digit.
Write a script to find the highest digit between 0-9 that makes it valid time.
Example 1
Input: $time = '?5:00'
Output: 1
Since 05:00 and 15:00 are valid time and no other digits can fit in the
missing place.
Example 2
Input: $time = '?3:00'
Output: 2
Example 3
Input: $time = '1?:00'
Output: 9
Example 4
Input: $time = '2?:00'
Output: 3
Example 5
Input: $time = '12:?5'
Output: 5
Example 6
Input: $time = '12:5?'
Output: 9
=cut
###############################################################################
#--------------------------------------#
# Copyright © 2022 PerlMonk Athanasius #
#--------------------------------------#
#==============================================================================
=comment
Interface
---------
If no command-line arguments are given, the test suite is run.
Algorithm
---------
Let the input be symbolized "wx:yz". There are 4 positions in which a digit can
be replaced by a question mark; each of these positions is treated as a sepa-
rate case:
1. ?x:yz - if x is 0, 1, 2, or 3, then the highest value of w is 2; other-
wise, it is 1.
2. w?:yz - if w is 2, then the highest value of x is 3; otherwise, it is 9.
3. wx:?z - the highest possible value of y is always 5.
4. wx:y? - the highest possible value of z is always 9.
=cut
#==============================================================================
use strict;
use warnings;
use Const::Fast;
use Test::More;
const my $TST_FLDS => 3;
const my $USAGE =>
qq[Usage:
perl $0 <time>
perl $0
<time> Time in the format "hh:mm" with one digit replaced by "?"\n];
#------------------------------------------------------------------------------
BEGIN
#------------------------------------------------------------------------------
{
$| = 1;
print "\nChallenge 194, Task #1: Digital Clock (Perl)\n\n";
}
#==============================================================================
MAIN:
#==============================================================================
{
my $args = scalar @ARGV;
if ($args == 0)
{
run_tests();
}
elsif ($args == 1)
{
my $time = parse_command_line();
print "Input: \$time = '$time'\n";
printf "Output: %s\n", find_highest_digit( $time );
}
else
{
error( "Expected 1 or 0 command-line arguments, found $args" );
}
}
#------------------------------------------------------------------------------
sub find_highest_digit
#------------------------------------------------------------------------------
{
my ($time) = @_;
my $hour_orig = substr $time, 0, 2;
my $hour_new = $hour_orig;
my $minute_orig = substr $time, 3, 2;
my $minute_new = $minute_orig;
my $digit;
if ($hour_orig =~ / ^ \? (\d) $ /x) # Hour: tens
{
substr( $hour_new, 0, 1 ) = $digit = ($1 < 4) ? 2 : 1;
}
elsif ($hour_orig =~ / ^ (\d) \? $ /x) # Hour: ones
{
substr( $hour_new, 1, 1 ) = $digit = ($1 < 2) ? 9 : 3;
}
elsif ($minute_orig =~ / ^ \? /x) # Minute: tens
{
substr( $minute_new, 0, 1 ) = $digit = 5;
}
else # Minute: ones
{
substr( $minute_new, 1, 1 ) = $digit = 9;
}
0 <= $hour_new < 24 or error( qq[Invalid hour "$hour_orig"] );
0 <= $minute_new < 60 or error( qq[Invalid minute "$minute_orig"] );
return $digit;
}
#------------------------------------------------------------------------------
sub parse_command_line
#------------------------------------------------------------------------------
{
my $time = $ARGV[ 0 ];
length( $time ) == 5
or error( 'The input string must be 5 characters long' );
substr( $time, 2, 1 ) eq ':'
or error( 'Hours and minutes must be separated by a colon' );
my $count = 0;
for my $i (0, 1, 3, 4)
{
my $c = substr $time, $i, 1;
$c =~ /([^0-9?])/
and error( qq[Invalid character "$1"] );
++$count if $c eq '?';
}
$count == 1
or error( 'The input string must contain exactly one question mark' );
return $time;
}
#------------------------------------------------------------------------------
sub error
#------------------------------------------------------------------------------
{
my ($message) = @_;
die "ERROR: $message\n$USAGE";
}
#------------------------------------------------------------------------------
sub run_tests
#------------------------------------------------------------------------------
{
print "Running the test suite\n";
while (my $line = <DATA>)
{
chomp $line;
my ($test_name, $n, $expected) = split / , \s* /x, $line, $TST_FLDS;
is find_highest_digit( $n ), $expected, $test_name;
}
done_testing;
}
###############################################################################
__DATA__
Example 1, ?5:00, 1
Example 2, ?3:00, 2
Example 3, 1?:00, 9
Example 4, 2?:00, 3
Example 5, 12:?5, 5
Example 6, 12:5?, 9
|
