Hashing and five popular hashing functions, Data Structure & Algorithms

Assignment Help:

Q. Explain the term hashing? Explain any five well known hash functions.                        

Ans:

Hashing method provides us the direct access of record from the file dosent matter where the record is in the file. This is made possible with the help of a hashing function H which map the key with the corresponding key address. It provides us with the key- to-address transformation.

Five well known hashing functions are as follows:

The Division Method: An integer key x is divided by the table size m and the remainder is occupied as the hash value. This may be defined as

H(x)=x%m+1

Take an example, x=42 and m=13, H(42)=45%13+1=3+1=4

The Midsquare Method: In this a key is multiplied by itself and the hash value is obtained by selecting an suitable number of digits from the middle of the square. The identical positions in the square must be used for all keys. Taking an example, if the key is 12345, square of this key is given by value 152399025. If 2 digit addresses is needed then position 4th and 5th can be chosen, giving address 39.

The Folding Method: In this a key is broken into several parts. Each part has the same length similar to that of the required address apart from the last part. The parts are added together, ignoring the last carry, we get the hash address for key K.
The multiplicative method:  In this technique a real number c  such  that  0

H(x)=[m(cx%1)]+1

In this,cx%1 is the fractional part of cx and [] denotes the greatest integer less than or equal to its own contents.

The Digit Analysis: In this method the addresses is formed by selecting and shifting digits of the original key. For a given set of key, the same positions in the key and same rearrangement of the pattern must be used. By taking an example a key 7654321 is transformed to the address 1247 by selecting the digits in the position 1,2,4 and 7 then by reversing the order.


Related Discussions:- Hashing and five popular hashing functions

Find error for curious number, #include #include int sumFact(int numb);...

#include #include int sumFact(int numb); int calculateFactorial(int digit); main() { int numb, sumfact; do{ printf ("Enter a number 1 to 9999\n"); scanf("%

Example of binary search, Let us assume a file of 5 records that means n = ...

Let us assume a file of 5 records that means n = 5 And k is a sorted array of keys of those 5 records. Let key = 55, low = 0, high = 4 Iteration 1: mid = (0+4)/2 = 2

Implementation of stack, In this unit, we have learned how the stacks are i...

In this unit, we have learned how the stacks are implemented using arrays and using liked list. Also, the advantages and disadvantages of using these two schemes were discussed. Fo

Explain multiplication method, Multiplication Method: The multiplication m...

Multiplication Method: The multiplication method operates in 2 steps. In the 1ststep the key value K is multiplied by a constant A in the range O

Non-recursive implementation of preorder traversal, For preorder traversal,...

For preorder traversal, in the worst case, the stack will rise to size n/2, where n refer to number of nodes in the tree. Another method of traversing binary tree non-recursively t

Storing street addresses with doubly linked lists, Write a C++ program with...

Write a C++ program with header and source les to store street addresses using the Doubly Linked List ADT. Modify the Node class from Lab Assignment 3 so that it becomes a node in

Explain circular queues, Circular Queues:- A more efficient queue repre...

Circular Queues:- A more efficient queue representation is get by regarding the array Q(1:n) as circular. It becomes more convenient to declare the array as Q(O: n-1), when  re

Quick sort method, Q. Explain quick sort? Sort the given array using quick ...

Q. Explain quick sort? Sort the given array using quick sort method. 24 56 47 35 10 90 82 31

Areas of use - sequential files, Sequential files are most frequently utili...

Sequential files are most frequently utilized in commercial batch oriented data processing where there is the concept of a master file on which details are inserted periodically. F

Algorithms & flowchart, write an algorithm to find the average number of oc...

write an algorithm to find the average number of occurances of MECHANIL in an english passage

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd