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

Algorithms, Write an algorithm to print all even numbers in descending orde...

Write an algorithm to print all even numbers in descending order and draw the flowchart

Illustrate the operations of the symbol abstract data type, The operations ...

The operations of the Symbol ADT The operations of the Symbol ADT are the following. a==b-returns true if and only if symbols a and bare identical. a symbol bin Unico

B-TREE and AVL tree diffrance, Explain process of B-TREE and what differen...

Explain process of B-TREE and what difference between AVL Tree Using Algorithms

Method for keeping two stacks within a single linear array, Q. Define a met...

Q. Define a method for keeping two stacks within a single linear array S in such a way that neither stack overflows until entire array is used and a whole stack is never shifted to

Four applications or implementation of the stack, Q. Write down any four ap...

Q. Write down any four applications or implementation of the stack.                                     Ans. (i)       The Conversion of infix to postfix form (ii)

space, What is Space complexity of an algorithm? Explain

What is Space complexity of an algorithm? Explain.

Representation of sets?, A set s is conveniently shown in a computer store ...

A set s is conveniently shown in a computer store by its characteristic function C(s). This is an array of logical numbers whose ith element has the meaning "i is present in s". As

Hash table, Q. Make the 11 item hash table resulting from hashing the given...

Q. Make the 11 item hash table resulting from hashing the given keys: 12, 44, 13, 88, 23, 94, 11, 39, 20, 16 and 5 by making use of the hash function h(i) = (2i+5) mod 11.

Write down the algorithm of quick sort, Write down the algorithm of quick s...

Write down the algorithm of quick sort. An algorithm for quick sort: void quicksort ( int a[ ], int lower, int upper ) {  int i ;  if ( upper > lower ) {   i = split ( a,

Explain expert system, 1. What is an expert system and where are they need...

1. What is an expert system and where are they needed? 2. What are the major issues involved in building an expert system?

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