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

Define an array, Define an array. Array is made up of same data structu...

Define an array. Array is made up of same data structure that exists in any language. Array is set of same data types. Array is the collection of same elements. These same elem

Array implementation of lists, In the array implementation of the lists, we...

In the array implementation of the lists, we will use the array to hold the entries and a separate counter to keep track of the number of positions are occupied. A structure will b

Minimum cost spanning trees, A spanning tree of any graph is only a subgrap...

A spanning tree of any graph is only a subgraph that keeps all the vertices and is a tree (having no cycle). A graph might have many spanning trees. Figure: A Graph

Asymptotic analysis, Asymptotic Analysis Asymptotic analysis is dependi...

Asymptotic Analysis Asymptotic analysis is depending on the idea that as the problem size grows, the complexity can be defined as a simple proportionality to some known functio

An algorithm to insert a node in beginning of linked list, Q. Write down an...

Q. Write down an algorithm to insert a node in the beginning of the linked list.                         Ans: /* structure containing a link part and link part

#titlestrings, given the string "Data Structures & , Algorithms", write a p...

given the string "Data Structures & , Algorithms", write a program that uses sequential search to return index of ''&''

Linear search, Linear search is not the most efficient way to search an ite...

Linear search is not the most efficient way to search an item within a collection of items. Though, it is extremely simple to implement. Furthermore, if the array elements are arra

Graph, For the following graph find the adjacency matrix and adjacency list...

For the following graph find the adjacency matrix and adjacency list representation of the graph.

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