use strict;
use warnings;

use Data::Dumper;

my $completed_courses = [ 
                       {
                         'type' => 'core',
                         'name' => 'Discrete Structures',
                         'title' => 'CS 130'
                       },
                       {
                         'type' => 'core',
                         'name' => 'Intro to Computer Science',
                         'title' => 'CS 140'
                       },
                        {
                         'type' => 'core',
                         'name' => 'C++ Programming',
                         'title' => 'CS 256'
                       }
                  ];

my $schedule = {
               'CS 130 Section 01' => {
                                        Course => 'CS 130',
                                        Time => '8:00 AM - 9:00 AM',
                                        'Class number' => 35465,
                                        Room => '8 302'
                                      },

              'CS 140 Section 01' => {
                                        Course => 'CS 140',
                                        Time => '8:00 AM - 9:00 AM',
                                        'Class number' => 35465,
                                        Room => '8 302'
                                      },
               'CS 256 Section 01' => {
                                        Course => 'CS 256',
                                        Time => '8:00 AM - 9:00 AM',
                                        'Class number' => 35465,
                                        Room => '8 302'
                                      },
              'CS 241 Section 02' => {
                                        Course => 'CS 241',
                                        Time => '8:00 AM - 9:00 AM',
                                        'Class number' => 35465,
                                        Room => '8 302'
                                      },
           };

for my $done (@{ $completed_courses }){
    my $title = $done->{title};
    for my $section (keys %$schedule){
        if ($schedule->{$section}{Course} eq $title){
            delete $schedule->{$section};
        }
    }
}

print Dumper $schedule;

##</code><code>##

$VAR1 = {
          'CS 241 Section 02' => {
                                   'Class number' => 35465,
                                   'Room' => '8 302',
                                   'Course' => 'CS 241',
                                   'Time' => '8:00 AM - 9:00 AM'
                                 }
        };