Direct Address Tables

1

• Direct Address Tables
• Hashing

2
Introduction to Hashing and Direct Address tables

• ?????
• ??? ??????? ???????? ????? ????? ??? ????? ??
  ?????? ???????? (???????), ??????? ????? ???????
  ?????
• Search
• Insert
• Delete

3
Introduction to Hashing and Direct Address tables

• ?????? ????? ????? ??????? ?????? ????????

4
Introduction Hashing and Direct Address tables

• ???? ?? ????? ?????? ???? ?? ?????? ?? ?????? ??
  ???? ??????? ?- worst case ?-average case
• w.c. a.c.
• Search ? (n) ? (n)
• Insert ? (1) ? (1)
• Delete ? (1) ?? ? (n) ? (1) ?? ? (n)

5
Direct Address tables (DA)

• ????? ???? DA ?? ??????? ????? ?- worst case
• Search ? (1)
• Insert ? (1)
• Delete ? (1)

6
Direct Address tables (DA)

• ?????
• ??? ?????x ???? ??? ???? keyx
• (?????? ??-?? ?????) .
• ?????
• ????? ??? x keyx
• ???? ?.?.

7
Direct Address tables (DA)

• ?????
• ???? ?- U ???? ?? ??????? ????????
• U0,1,... ,m-1. U m
• ???? ?- K ?? ?? ??????? ????????. K n
• ???? ?- T0,,m-1 ????
• TkeyxAddressx?? ?K x
• TkeyxNil?? ?K x
• (??? ?? ??????)

8
Direct Address tables (DA)

• ?????
• ??? ???? ? T0, ,m-1
• ????? ????

9
Hashing

• ?? ????? ????? Hashing(?????? ???????) ???????
• worst case average case
• Search ? (n) ? (1)
• Insert ? (1) ? (1)
• Delete ? )1) ?? ? (n) ? (1)

10
Hashing

• Chaining
• Open Addresses