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

Creation of Heap, Q. Create a heap with the given list of keys: ...

Q. Create a heap with the given list of keys: 8, 20, 9, 4, 15, 10, 7, 22, 3, 12                                                  Ans: Creation

Define tree ?, A tree is a non-empty set one component of which is designat...

A tree is a non-empty set one component of which is designated the root of the tree while the remaining components are partitioned into non-empty groups each of which is a subtree

Estimate best first search nodes , Given the following search tree, state t...

Given the following search tree, state the order in which the nodes will be searched for breadth first, depth first, hill climbing and best first search, until a solution is reache

Variable length codes, Variable length codes (Niveau I) Code the following ...

Variable length codes (Niveau I) Code the following sequence of integers (2, 4, 2, 8, 3, 1, 4, 5, 13, 2) with • unary codes • ? codes • d codes • Rice codes (for a suitable l) and

Program, insertion and deletion in a tree

insertion and deletion in a tree

Hotel reservation system, pls i want a psuedo code for hotel reservation sy...

pls i want a psuedo code for hotel reservation system.

Adjacency matrix, Q. Give the adjacency matrix for the graph drawn below:  ...

Q. Give the adjacency matrix for the graph drawn below:                                                 Ans: Adjacency matrix for the graph given to us

Binary search trees, In this unit, we discussed Binary Search Trees, AVL tr...

In this unit, we discussed Binary Search Trees, AVL trees and B-trees. The outstanding feature of Binary Search Trees is that all of the elements of the left subtree of the root

Hash function, Q. Define the graph, adjacency matrix, adjacency list, hash ...

Q. Define the graph, adjacency matrix, adjacency list, hash function, adjacency matrix, sparse matrix, reachability matrix.

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