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

Binary search trees, A Binary Search Tree is binary tree which is either em...

A Binary Search Tree is binary tree which is either empty or a node having a key value, left child & right child. By analyzing the above definition, we notice that BST comes int

Time complexity of merge sort and heap sort algorithms, What is the time co...

What is the time complexity of Merge sort and Heap sort algorithms? Time complexity of merge sort is O(N log2 N) Time complexity of heap sort is   O(nlog2n)

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

Binry trees, Build a class ?Node?. It should have a ?value? that it stores ...

Build a class ?Node?. It should have a ?value? that it stores and also links to its parent and children (if they exist). Build getters and setters for it (e.g. parent node, child n

Need it urgently, Write an assembly program to separate the number of posit...

Write an assembly program to separate the number of positive numbers and negative numbers from a given series of signed numbers.

Construct a minimum spanning tree, Construct G for α, n, and W given as com...

Construct G for α, n, and W given as command line parameters. Throw away edges that have an asymmetric relation between nodes. That is, if A is connected to B, but B is not connect

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

Pseudocodes, how to draw a 5 inch square on the screen using * symbol

how to draw a 5 inch square on the screen using * symbol

Linked list implementation of a dequeue, Double ended queues are implemente...

Double ended queues are implemented along doubly linked lists. A doubly link list can traverse in both of the directions as it contain two pointers namely left pointers and righ

Infix expression to postfix form using the stack function, Q. Convert the f...

Q. Convert the following given Infix expression to Postfix form using the stack function: x + y * z + ( p * q + r ) * s , Follow general precedence rule and suppose tha

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