var default_room = 2;

function highlight_room(room) {
 elem = document.getElementById('map');
 elem.src='images/map_'+room+'.gif';
}

function unhighlight_room() {
 elem = document.getElementById('map');
 elem.src='images/map_'+default_room+'.gif';
}

function change_room(room) {
 var room_photo = document.getElementById('room_photo');
 default_room = room;
 room_photo.className = 'room_'+room;
}