Treaps and a DVD Checkout System

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Treaps and a DVD Checkout System

• Jim Moiani
• Michael Crocker

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Its a tree its a heap

• A treap is a balanced binary search tree
• Its node is similar to a binary search trees
  node (has pointer to left and right, and a key)
• Also contains a random priority
• Since the priorities are randomly assigned, nodes
  can be inserted like they would for a binary
  search tree, and then rotated so that the
  priorities of the nodes also maintain the
  properties of a heap

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What do you use it for?

• We used treaps to create a DVD rental system
• Separate treaps for in-stock movies, checked-out
  movies, and a record of the membership
• Features include ability to add new movies and
  members, display a members records, and check
  movies in and out

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So what are the benefits?

• Provides all the functionality of binary search
  trees, like inorder traversal, but also
  guarantees a T(lg n) search time
• Of course, this is given that youve made enough
  insertions so that the priorities approach a
  normal distribution

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Whats left to add? Possible Improvements

• A GUI
• Provides overdue notification could interface
  with a member account system (debit credit cards
  for overdue movies?)
• A few member functions work by entering the
  member number could interface with a scanner
• More info for DVDs, like UPC, release date,
  review notes, and other information

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And one more

• More treaps which are pointers to our member
  classes, which can be referenced to sort and
  display other categories quickly and easily
• Sort DVDs by rating, release year, title, and so
  on
• Sort members by name, location, member number
• All without searching the whole treap!

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And now, a demonstration