Junaid (Quick Sort)

8/14/2019 Junaid (Quick Sort)

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By the Name ofBy the Name of

AllahAllah. the most merciful & mighty. the most merciful & mighty

.Presentation No 1.Presentation No 1

Junaid KhanC.No 33

(Morning Shift)


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Topic :Topic :QUICK SORTQUICK SORT

Quick sort is very Popular sorting

method. C.A.R Hoare introduced it in

1962. It is very important method ofinternal sorting. According to this

algorithm it is faster and easier to sort

two small arrays instead of one largerarray. The quick sort is an algorithm of

Divide-and-conquer. It is also called

Partition exchange sort.


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Explaining this mechanism with anEx

plaining this mechanism with an

ExampleExam

ple42 31 5 6 7

T

i j

40 30 60 20 10 70 50

Let T be array with 7 elements we will start the

comparison form right to left .we use twopointing variables I and j.

i= Points to 1st location & j= To last location


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50701020603040

Compare T[j] with T[I] , if T[j] is greater than

T[I] then decrement the j pointerby 1 until

T[j]>T[i].

If at any point T[j]


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50704020603010T

i i i

If at any point T[i]>T[j] and j>I then swap T[i]

and T[j].

And start from right to left comparison, if

T[j]T[i]).

j

And start comparison from left to right, if T[i]


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50704020603010

i i i j

50706020403010

i jj


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50706040203010

i ji

At some point I and j will become equal this

shows that the element of left side of that areless than the middle element and elements at

right side are greater than the element

position I or j.So this is the ourdividing point the elements of

left side are left sub array and the elements on

right side are right sub array.

T


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Now we will use a stack to postpone the

larger sub problem (sub array) by pushing it

on the top of the stack and continue with the

smaller array and use the same procedure asused above ,after that we will pop the stack

top and start the same procedure with that

sub array and so on.

In this example we have both arrays equal so

we will push right array on the stack top and

proceed with left sub array.

203010T

j ji


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203010

302010

The left sub array become sorted now

we will sort the right sub array as follow

j

j

i i

i

j

j

T

T


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706050

607050

507060

T

T

T

5

5

5

6

6

67

7

7

i

i

i j

j

j

i

j

N th i ht b bN th i ht b b


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Now the right sub array becomeNow the right sub array become

also sorted so we have followingalso sorted so we have following

sorted arraysorted array

70605040302010T


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You are notKids

Lilo

Any

Question

?


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MESSAGEMESSAGESuccess is not always

permanent and Failure is notAlways Final, So don't loss

effort until and unless your

.Victory make History

)HITLER(


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!Have a nice day

Thanks a lot for yourThanks a lot for yoursincere Attentionsincere Attention

Junaid (Quick Sort)

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