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

Algorithm, algorithm to search a node in linked list

algorithm to search a node in linked list

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.

Multiple stack in single dimensional array, Implement multiple stacks in a ...

Implement multiple stacks in a single dimensional array. Write algorithms for various stack operations for them.

What is assertions, What is Assertions Introduction At every point...

What is Assertions Introduction At every point in a program, there are generally constraints on the computational state that should hold for program to be correct. For ins

Examination, Write an algorithm for binary search. What are its limitations...

Write an algorithm for binary search. What are its limitations? .

Undirected graph, Graphs are data structures which consist of a set of vert...

Graphs are data structures which consist of a set of vertices & a set of edges which connect the vertices. A graph where the edges are directed is called directed graph. Or else, i

Program of insertion of an element in list, Program will demonstrate the in...

Program will demonstrate the insertion of an element at desired position /* Inserting an element into contiguous list (Linear Array) at particular position */ /* contiguous_

Functions and modelling the data flows, Read the scenario (Pickerings Prope...

Read the scenario (Pickerings Properties). (a) List the functions of the system, as perceived by an external user. (b) List the external entities. Note that because we are mo

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