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

Non-recursive implementation of preorder traversal, For preorder traversal,...

For preorder traversal, in the worst case, the stack will rise to size n/2, where n refer to number of nodes in the tree. Another method of traversing binary tree non-recursively t

Rules for abstract data type-tree, null(nil) = true                     // ...

null(nil) = true                     // nil refer for empty tree null(fork(e, T, T'))= false   //  e : element , T and T are two sub tree leaf(fork(e, nil, nil)) = true leaf(

Infix expression has balanced parenthesis or not, Q. By making use of stack...

Q. By making use of stacks, write an algorithm to determine whether the infix expression has balanced parenthesis or not.

Write an algorithm to measure daily temperatures, A geography class decide ...

A geography class decide to measure daily temperatures and hours of sunshine each day over a 12 month period (365 days) Write an algorithm, using a flowchart that inputs tempera

Data structure queue, In this unit, we described about the data structure Q...

In this unit, we described about the data structure Queue. It had two ends. One is front from where the elements can be removed and the other is rear where the elements can be inse

Program to implementing stack using linked lists, include include i...

include include include /* Definition of structure node */ typedef struct node { int data; struct node *next; } ; /* Definition of push function */

FIRST function in the compiler construction, I need a recursive algorithm t...

I need a recursive algorithm to implement the FIRST function to any grammar

Write a program for linear search, In the book the following methods are pr...

In the book the following methods are presented: static void selectionSort(Comparable[] list) static void insertionSort(Comparable[] list) static boolean linearSearch(Comparable

If, 1. Start 2. Get h 3. If h T=288.15+(h*-0.0065) 4. else if h T=2...

1. Start 2. Get h 3. If h T=288.15+(h*-0.0065) 4. else if h T=216.65 5. else if h T=216.65+(h*0.001) 6. else if h T=228.65+(h*0.0028) 7. else if h T=270.65 8.

Dijkstras algorithm, Djikstra's algorithm (named after it is discovered by ...

Djikstra's algorithm (named after it is discovered by Dutch computer scientist E.W. Dijkstra) resolves the problem of finding the shortest path through a point in a graph (the sour

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