Selection sort is a sorting algorithm that works by repeatedly finding the minimum element from an unsorted sublist and putting it at the front. It has the following steps: 1. Start with an unsorted list. 2. Find the minimum element in the list and swap it with the first element. 3. Repeat step 2 for the remaining elements, each time considering one less element at the front that is already in sorted order. The algorithm runs in O(n2) time as the inner loop needs to run n-1 times for n elements. It works for both ascending and descending order by changing the comparison operator in the inner loop.

1. SELECTION SORT
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2. Submitted by:
1 Arifarina
2 sakil
3 sabuj sarkar
4 Himu
Submitted to:
Mr.Tahzibul Islam
Lecturer,Department of
cse.Dhaka International
University.
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DATA STRUCTURES-CSE 205
PRESENTATION

3. ROAD MAP
1 Definition
2 Example
3 Algorithm
4 Ascending And Dscending order.
6 Mathematical definition
7Question And Answer
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4. 4
▪The selection sort is a combination of searching
and sorting.
▪In selection sort, sorting is done after selecting a
particular smallest or largest element from an array
and shifted it to a particular location in an array.
▪During each pass, the unsorted element with the
smallest (or largest) value is moved to its proper
position in the array.

5. 5
▪Let's look at our same table of elements
Using a selection sort for ascending order
▪The number of times the sort passes through
the array is one less than the number of items
in the array.

6. 6
Selection Sort Example
Sorted Unsorted
23 78 45 8 32 56 Original List
8 78 45 23 32 56 After pass 1
8 23 45 78 32 56 After pass 1
8 23 32 78 45 56 After pass 1
8 23 32 45 78 56 After pass 1
8 23 32 45 56 78 After pass 1

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Ascending order
Algorithm: Selection sort(L,N)
1 Repeat steps 2 to 6 for I=1 to N
2 set min:=I
3 Repeat steps 4 & 5 for J=I+1 to N
4 if list [J]<list [min] then
5 set lin:=J
6 swap (list [I],list [min])
7 End.
L=List of items.
N=Totel number of
items in the list .

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▪ In the selection sort, the inner loop finds the next
smallest value and the outer loop places that value
into its proper location.
Array 40 50 60 10 30 20
1-
pass
10 50 60 40 30 20
2-
pass
10 20 60 40 30 50
3-
pass
10 20 30 40 60 50
4-
pass
10 20 30 40 60 50
5-
pass
10 20 30 40 50 60

9. 9
Dscending order
Algorithm:selection sort(L,N)
1 Repeat steps 2 to 6 for I=1 to N
2 min:=I
3 Repeat steps 4 & 5 for J=I+1 to N
4 if list [J]>list [mix] then
5 set mix:=J
6 swap(list [I],list-[min])
7 End
L=list of items
N=Totel number
of items in the
list .

10. 10
Array 70 50 11 10 40 20
1-
pass
70 50 11 10 40 20
2-
pass
70 50 11 10 40 20
3-
pass
70 50 40 10 11 20
4-
pass
70 50 40 20 11 10
5-
pass
70 50 40 20 11 10
▪In the selection sort, the inner loop finds the
next largest value and the outer loop places that
value into its proper location.

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i:0; j:1 (7-1);min=I;if(arr[j]<arr[min]) {min=j;} finally sw
(a[i],a[min])
89 45 68 90 29 34 17
» 17| 45 68 90 29 34 89
i:1;j:2 (7-1); min=I;if(arr[j]<arr[min]) {min=j;} finally sw
(a[i],a[min])
17|45 68 90 29 34 89
»17|29 |68 90 45 34 89

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i:2;j:3 (7-1); min=I;if(arr[j]<arr[min]) {min=j;}finally s
(a[i],a[min])
17|29 68 90 45 34 89
17|29|34| 90 45 68 89
Complexity is O(n2).
Kitkat

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* Any query?
* Any question or any point which you doesn’t

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THANK YOU!