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

Procedures, what is far and near procedures in system programming?

what is far and near procedures in system programming?

What is an unreachable code assertion, What is an unreachable code assertio...

What is an unreachable code assertion An unreachable code assertion can be placed at the default case; if it's every executed, then program is in an erroneous state. A loop in

Size of stack, The size of stack was declared as ten. Thus, stack cannot ho...

The size of stack was declared as ten. Thus, stack cannot hold more than ten elements. The major operations which can be performed onto a stack are push and pop. However, in a prog

Merging 4 sorted files containing 50, Merging 4 sorted files having 50, 10,...

Merging 4 sorted files having 50, 10, 25 and 15 records will take time  O (100)

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

Find longest repeat prefix of string - linear time algorithm, 1. A string s...

1. A string s is said to be periodic with a period α, if s is α k for some k > 2. (Note that α k is the string formed by concatenating k times.) A DNA sequence s is called a tand

Linked list, create aset of ten numbers.then you must divide it into two s...

create aset of ten numbers.then you must divide it into two sets numbers which are set of odd numbers and set of even numbers.

The search trees are abstract data types, the above title please send give ...

the above title please send give for the pdf file and word file

State hsv colour model, HSV Colour Model Instead of a set of colour pri...

HSV Colour Model Instead of a set of colour primaries, the HSV model uses colour descriptions that have a more intuitive appeal to a user. To give a colour specification, a use

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