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#! /opt/local/bin/perl
#
# whos_open_for_business.pl
#
# TASK #2
# Is the room open?
# There are 500 rooms in a hotel with 500 employees having keys to all the rooms.
# The first employee opened main entrance door of all the rooms. The second
# employee then closed the doors of room numbers 2,4,6,8,10 and so on to 500. The
# third employee then closed the door if it was opened or opened the door if it
# was closed of rooms 3,6,9,12,15 and so on to 500. Similarly the fourth employee
# did the same as the third but only room numbers 4,8,12,16 and so on to 500. This
# goes on until all employees has had a turn.
# Write a script to find out all the rooms still open at the end.
#
# 2020 colin crain
## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
use warnings;
use strict;
use feature ":5.26";
## ## ## ## ## MAIN
my $SIZE = 500;
my @hotel = (0) x $SIZE;
for my $emp (1..$SIZE) {
my @doors = map { $_ % $emp == 0 ? 1 : 0 } ( 1..$SIZE );
for my $idx ( 0..$SIZE-1 ) {
$hotel[$idx] = $hotel[$idx] ^ $doors[$idx];
}
}
for (0..$SIZE-1) {
printf "room %3s is open\n", $_+1 if $hotel[$_];
}
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