PPT-Maps and Hashing Eric Roberts

CS 106B February 15 2013 Simplifying the Map Abstraction Although templates offer considerable flexibility when you are designing a collection class they also complicate both the interface and the implementation making them harder to follow. Our protocols are particularly designed for use with ery lar ge netw orks such as the Internet where delays caused by hot spots can be se ere and where it is not feasible for ery serv er to ha complete information about the current state of the enti 1 Overview Hashing is a great practical tool with an interesting and su btle theory too In addition to its use as a dictionary data structure hashing also comes up in many di 64256erent areas including cryptography and complexity theory In this lectu The analysis uses only very basic and intuitively understandable concepts of probability theory and is meant to be accessible even for undergraduates taking their 64257rst algorithms course 1 Introduction dictionary is a data structure for storing a Up to this point the greatest drawback of cuckoo hashing appears to be that there is a polynomially small but practically signicant probability that a failure occurs during the insertion of an item requiring an expensive rehashing of all items in th COL 106. Shweta Agrawal, . Amit. Kumar. Slide Courtesy : Linda Shapiro, . Uwash. Douglas W. Harder, . UWaterloo. 12/26/03. Hashing - Lecture 10. 2. The Need for Speed. Data structures we have looked at so far. Approximate Near Neighbors. Ilya Razenshteyn (CSAIL MIT). Alexandr. . Andoni. (Simons Institute). Approximate Near Neighbors (ANN). Dataset:. . n. points in . d. dimensions. Query:. a point within . Plan. I spent the last decade advising on numerous cases where hash tables/functions were used. A few observations on . What data structures I’ve seen implemented and where. What do developers think, were they need help. Consider a set of data with N data items stored in some data structure. We must be able to insert, delete & search for items. What are possible ways to do this? What is the complexity of each structure & method ?. In static hashing, function . h. maps search-key values to a fixed set of . B. . buckets, that contain a number of (K,V) entries.. . . Problem: d. atabases . grow . (or shrink) . with time. . If initial number of buckets is too small, and file grows, performance will degrade due to too much overflows.. What is a hashing function?. Fingerprint for a given piece of data. Typically generated by a mathematical algorithm. Produces a fixed length string as its . output. Hashes are sometimes . called a . checksum or message digests. . Presenter: Alicia McGee. Email: . amcgee@mobilemcps.org. Make a copy of this to take notes!. Maps and Geography . We want students to become global students….. So….. Students should be able to:. CS 106B. February 27. , . 2013. Outline. A review . the . graphtypes.h. and . graph.h. interfaces. 1.. E. xamples of depth-first and breadth-first search. 3.. Dijkstra’s. shortest-path algorithm. Nifty Assignments. SIGCSE 2013. March 9, 2013. This is not your typical assignment. Ceux. . ne . sont. pas . . vos. . devoirs . typiques. The. . TurtleGraphics. . Assignment. Traditional . Amjad. . Daoud. , Ph.D.. http://iswsa.acm.org/mphf. Practical Perfect Hashing for very large Key-Value Databases . Abstract. This presentation describes a practical algorithm for perfect hashing that is suitable for very large KV (key, value)...