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

Whether a binary tree is a binary search tree or not, Write an algorithm to...

Write an algorithm to test whether a Binary Tree is a Binary Search Tree. The algorithm to test whether a Binary tree is as Binary Search tree is as follows: bstree(*tree) {

Implement an open hash table, In a chained hash table, each table entry is ...

In a chained hash table, each table entry is a pointer to a collection of elements. It can be any collection that supports insert, remove, and find, but is commonly a linked list.

Explain open addressing, Open addressing The easiest way to resolve a c...

Open addressing The easiest way to resolve a collision is to start with the hash address and do a sequential search by the table for an empty location.

Calculates partial sum of an integer, Now, consider a function that calcula...

Now, consider a function that calculates partial sum of an integer n. int psum(int n) { int i, partial_sum; partial_sum = 0;                                           /* L

Graphs, In this unit, we will describe a data structure called Graph. Actua...

In this unit, we will describe a data structure called Graph. Actually, graph is a general tree along no parent-child relationship. In computer science, Graphs have several applica

Frequency count, what is frequency count with examble

what is frequency count with examble

Random searching, write a program that find,search&replace a text string

write a program that find,search&replace a text string

BST has two children, If a node in a BST has two children, then its inorder...

If a node in a BST has two children, then its inorder predecessor has No right child

Basic organization of computer system, what happen''s in my computer when ...

what happen''s in my computer when i input any passage

Reverse order of elements on a slack, Q. Describe the representations of gr...

Q. Describe the representations of graph. Represent the graph which is given to us using any two methods Ans: The different ways by which we can represent graphs are:

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