5. Dynamic Optimality I

preview_player
Показать описание
MIT 6.851 Advanced Data Structures, Spring 2012
Instructor: Erik Demaine

Dynamic optimality: binary search trees, analytic bounds, splay trees, geometric view, greedy algorithm

License: Creative Commons BY-NC-SA
Рекомендации по теме
Комментарии
Автор

1:05 - 1:58 central question: is there one "best" BST?
1:58 - 9:30 BST model of computation (more restricted than pointer machine model)
9:30 - 11:23 sequential access property
11:23 - 13:40 dynamic finger property
13:40 - 16:12 entropy property (it is static optimum for BST)
16:12 - 19:38 working set property
19:38 - 24:50 unified property
24:50 - 28:40 dynamic optimality
29:00 - 34:05 conjectured dynamic optimum: splay trees
34:05 - 1:12:17 geometric view
1:12:17 - 1:22:40 greedy algorithm, split trees

PS: he is using "space" instead of "keys" (or key-space) on the axis. for example k3 is smaller than k4.

aleksagordic
Автор

At 30:32, it should be rotate x, rotate x.  Rotating y when y is the root of the tree is undefined.  :/

hyralt
Автор

Here my brain started hurting a bit. I'm confused with the online greedy online algorithm: at each step you have a BST, and key to look up. On the one hand to do it in BST computation model you have to visit all nodes from the root to the node with the key. OTOH you have a geometric view that prescribes which nodes should be visited during this step to make an arboreally satisfied set. How on earth are they going to be the same?

PaulGraphov
Автор

Using 'space' for the other axis is confusing. Why don't you simply write keys?

SaadTaameOfficial