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Unformatted text preview: CSE 2320 Notes 9: Linked Lists (Last updated 10/6/11 8:11 PM) Sedgewick 3.3, 2.6, 12.3, 3.5, 3.4 9.A. S INGLY- LINKED ( FORWARD ) L ISTS . Links may be: Pointers Subscripts Disk addresses Web URLs (a logical address vs. a physical address in the other three cases) If the nodes have a key (i.e. a dictionary), should the list be ordered (ascending) or unordered? Ordered: If node y is the physical successor of x , then y is the logical successor of x . Unordered: No relationship between adjacent nodes. ASSUMPTION: Uniform access probabilities equal likelihood for accessing each of n keys expected probes hit miss unordered ordered n + 1 2 n + 1 2 n + 1 2 n 1 + 2 + + n n = n n + 1 ( ) 2 n = n + 1 2 Most applications have many more hits than misses. Many applications, however, need ordered retrieval (L OGICAL S UCCESSOR , L OGICAL P REDECESSOR ). 2 9.B. K EEPING L INKED L IST C ODE S IMPLE AND E FFICIENT . a. Header dummy node at beginning of list (even if no other nodes). Avoids first node special cases: D ELETE U NION This pointer never changes Can be wasteful if an application needs large number of very short lists. b. Sentinel dummy element at end of unordered table, unordered list, or tree....
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