What is Polyphase Sort, Data Structure & Algorithms

Assignment Help:
One of the best known methods for external sorting on tapes is the polyphase sort.

Principle: The basic strategy of this sort is to distribute ordered initial runs of predetermined size on the available tapes and then to repeatedly merge these runs in multiple phases in which each phase has a predetermined number of merges before a new target tape is selected.

To distribute the initial runs a Fibonacci distribution is adopted. After the distribution of the runs according to Fibonacci distribution, the merging procedure is continued until the tape with the least number of run lists is empty. When this occurs the remaining working tapes are logically rotated such that the newly emptied tape becomes the new target tape and the old target tape then becomes one of the working tapes to be merged. The sort ends when all runs are merged into one.

Let the number of tapes be T and p = T - 1. The Fibonacci distribution for p = 3 is given.

Level

s
Tape
Total number of runs
1
2
3
1
0
0
1
1
2
1
1
1
3
3
1
2
2
5
4
2
3
4
9
5
4
6
7
17
6
7
11
13
31
7
13
20
24
57
8
24
37
44
105
9
44
68
81
193
Algorithm:

1. Let A be the list of N unsorted elements and R be the number of runs.

2. Let T1, T2, T3 and T4 be the tapes on which sorting is done.

3. Split the list A into R=N runs so that each run has only one element.

4. If R is not equal to perfect Fibonacci distribution then add dummy records to bring up perfect Fibonacci distribution.

5. Distribute the records in the remaining tapes according to the Fibonacci distribution.

6. Merge 3 runs, one from each tape and put into next empty tape.

7. Repeat step 6 till a single run is generated.

Related Discussions:- What is Polyphase Sort

State in brief about assertion, State  in brief about assertion Asser...

State  in brief about assertion Assertion: A statement which should be true at a designated point in a program.

Draw trace table and determine output of number, Draw trace table and deter...

Draw trace table and determine output from the following flowchart using following data: Number = 45, -2, 20.5

Rl rotation - avl tree, Example: (Double left rotation while a new node is ...

Example: (Double left rotation while a new node is added into the AVL tree (RL rotation)) Figure: Double left rotation when a new node is inserted into the AVL tree A

Homework, Write a recursive function the computes the number of digits in a...

Write a recursive function the computes the number of digits in a positive integer n. For example if n = 6598, the function should return 4. Find a variant expression and a thresho

Queues, what is the difference between data type and abstract data type

what is the difference between data type and abstract data type

Enumerate about the data structure, Enumerate about the Data structure ...

Enumerate about the Data structure An arrangement of data in memory locations to signify values of the carrier set of an abstract data type. Realizing computational mechanis

The searching technique that takes o (1) time to find a data, The searching...

The searching technique that takes O (1) time to find a data is    Hashing is used to find a data

Data flow diagrams, How to construct a data flow diagram for a college assi...

How to construct a data flow diagram for a college assignment and marking systemA

Circular doubly link list, what is circular doubly link list?write down the...

what is circular doubly link list?write down the algorithm for insertion of elements in circular doubly link list

Define a tree and list its properties, QUESTION (a) Define a tree and l...

QUESTION (a) Define a tree and list its properties. (b) By showing all your workings, draw the spanning tree for the following graph based on the Breadth-First-Search algori

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