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

Hash tables, Q. Explain the Hash Tables, Hash function and Hashing Techniqu...

Q. Explain the Hash Tables, Hash function and Hashing Techniques properly?             A n s . H as h Table is explained as follows : A hash table is a data struc

Array vs. ordinary variable, Q. Describe what do you understand by the term...

Q. Describe what do you understand by the term array? How does an array vary from an ordinary variable? How are the arrays represented in the specific memory?

Java, Ask consider the file name cars.text each line in the file contains i...

Ask consider the file name cars.text each line in the file contains information about a car ( year,company,manufacture,model name,type) 1-read the file 2-add each car which is repr

State an algorithm which inputs 3 - digit code for 280 items, A small shop ...

A small shop sells 280 different items. Every item is identified by a 3 - digit code. All items which start with a zero (0) are cards, all items which start with a one (1) are swee

Deletion of a node from an avl tree, For AVL trees the deletion algorithm i...

For AVL trees the deletion algorithm is a little more complicated as there are various extra steps involved in the deletion of node. If the node is not a leaf node, then it contain

Explain dijkstra''s algorithm, Explain Dijkstra's algorithm Dijkstra's ...

Explain Dijkstra's algorithm Dijkstra's algorithm: This problem is concerned with finding the least cost path from an originating node in a weighted graph to a destination node

Multiqueue, data structure for multiqueue

data structure for multiqueue

Primitive data structure, Primitive Data Structure These are the basic ...

Primitive Data Structure These are the basic structure and are directly operated upon by the machine instructions. These in general have dissimilar representations on different

Delete a given node from a doubly linked list, Algorithm to Delete a given ...

Algorithm to Delete a given node from a doubly linked list Delete a Node from Double Linked List DELETEDBL(INFO, FORW, BACK, START, AVAIL,LOC) 1. [Delete Node] Set FOR

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