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

STACK, WHAT IS THE PURPOSE OF STACK IN C

WHAT IS THE PURPOSE OF STACK IN C

Arrays, This unit discussed about data structure called Arrays. The easiest...

This unit discussed about data structure called Arrays. The easiest form of array is a one-dimensional array which may be described as a finite ordered set of homogeneous elements

Multiqueue, data structure for multiqueue

data structure for multiqueue

Database design and sql queries, In assignment, you have already started th...

In assignment, you have already started the process of designing a database for the Beauty Salon mini-case (enclosed again below), mainly in the phase of conceptual database design

How will you represent a max-heap sequentially, How will you represent a ma...

How will you represent a max-heap sequentially? Max heap, also known as the descending heap, of size n is an almost complete binary tree of n nodes such that the content of eve

Convert graph into tree, How can we convert a graph into a tree ? Do we hav...

How can we convert a graph into a tree ? Do we have any standardized algorithm for doing this?

State the complex reallocation procedure, State the complex reallocation pr...

State the complex reallocation procedure Some languages provide arrays whose sizes are established at run-time and can change during execution. These dynamic arrays have an in

Comparisons between linear and binary search, Comparative Study of Linear a...

Comparative Study of Linear and Binary Search Binary search is lots quicker than linear search. Some comparisons are following: NUMBER OF ARRAY ELEMENTS EXAMINED array

Define strictly binary tree, Define Strictly Binary Tree Strictly Bina...

Define Strictly Binary Tree Strictly Binary Tree: - If each non leaf node in binary tree has non empty left and right sub-trees , then the tree is known as a strictly binary t

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