## Algorithm to sort a given list by quick sort method, Data Structure & Algorithms

Assignment Help:

Q. Write down an algorithm to sort a given list by making use of Quick sort method. Describe the behaviour of Quick sort when input given to us is already sorted.

Ans.

Algorithm for Quick Sort is written below

QUICK(A, N, BEG, END, LOC)

Here A is an array with N element. Parameter BEG

and END comprises the   boundary value of the sub

list of A to which this method applies. LOC keeps track of the position of the first element A[BEG] of the sublist during the particular procedure. The local varrible LEFT     and  RIGHT will contain the boundary value of the list elements that have not been scanned.

1. [Initialize]   Set LEFT:=BEG, RIGHT;=END and LOC:=BEG.

2. [Scan from left to right]

(a) Repeat while A[LOC] <=A[RIGHT] and LOC!=RIGHT; RIGHT:=RIGHT-1; [End of loop]

(b)If LOC= RIGHT, then Return;

(c)If A[LOC ] > A[RIGHT],then: [Interchange    A[LOC] and A[RIGHT]] TEMP:=  A[LOC]  ,A[LOC] =  A[RIGHT] , A[RIGHT] :=TEMP;

(i) Set LOC =RIGHT

(ii)      Go to step 3

3.[Scan from left to right]

repeat while A[LEFT] <=A[LOC] and  LEFT!= LOC; LEFT := LEFT +1; [End of loop]

(a) If LOC  =LEFT, then Return;

(b) If  A[LEFT]  > A[LOC] ,then

(i) [Interchange A[LEFT]  and A[LOC]] TEMP:=A[LOC],A[LOC]:=A[LEFT] . A[LEFT]:= TEMP

(ii) Set LOC :=LEFT (iii) Go to Step 2; [End of if structure]

(Quicksort) This algorithm sorts an array A with N elements.

1. [Intialize.] TOP := NULL

2. [Push boundary values of A onto stacks when A has 2 or more elements.]

If  N>1, then: TOP+1,LOWER :=1, UPPER : =N

3. Repeat steps 4 to 7 while TOP != NULL.

4. [Pop sublist from stacks.]

Set BEG: =LOWER[TOP], END:=UPPER[TOP], TOP:=TOP-1.

5. Call QUICK (A, N, BEG, END, LOC). [ Push left

sublist onto stacks when it has 2 or more elements.]

If BEG < LOC -1, then:

TOP:= TOP+1, LOWER[TOP] := BEG, UPPER[TOP]= LOC -1.

[End of If structure.]

6. [Push right sublist onto stacks when it has 2

or more elements.]

If  LOC +1< END , then:

TOP := TOP+1, LOWER[TOP] := LOC +1, UPPER[TOP] := END.

[End of If structure .] [End of Step 3 loop.]

7. Exit.

The behaviour of quick sort when the list is sorted is of order O(n2) as this is the worst case for quicksort

#### Sequential files, In this section, we will discuss about Sequential file or...

In this section, we will discuss about Sequential file organization. Sequential files have data records stored in a particular sequence. A sequentially organized file might be stor

#### Interest, I =PR/12 Numbers of years .Interest rate up to 1yrs ...

I =PR/12 Numbers of years .Interest rate up to 1yrs . 5.50 up to 5yrs . 6.50 More than 5 yrs . 6.75 design an algorithm based on the above information

#### Stack, implement multiple stacks ina single dimensional array. write algori...

implement multiple stacks ina single dimensional array. write algorithams for various stack operation for them.

#### Data mining classification, do you have expert in data mining ?

do you have expert in data mining ?

#### Algorithm, write an algorithm for the gpa of six students

write an algorithm for the gpa of six students

#### Graphs, In this unit, we will describe a data structure called Graph. Actua...

In this unit, we will describe a data structure called Graph. Actually, graph is a general tree along no parent-child relationship. In computer science, Graphs have several applica

#### What is ruby, What is Ruby Ruby has numerous simple types, including nu...

What is Ruby Ruby has numerous simple types, including numeric classes such as Integer, Fixnum, Bignum, Float, Big Decimal, Rational, and Complex, textual classes like String,

#### The two famous methods for traversing, The two famous methods for traversin...

The two famous methods for traversing are:- a) Depth first traversal b) Breadth first

#### Naïve recursive algorithm for binomial coefficients, How many recursive cal...

How many recursive calls are called by the naïve recursive algorithm for binomial coefficients, C(10, 5) and C(21, 12) C(n,k){c(n-1,k)+c(n-1,k-1) if 1 1 if k = n or k = 0

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