Implementation of Insertion Sort Algorithm and calculating the Efficiency of the Algorithm

1. Data Structures and Algorithms
Session 4Ver. 1.0
Insertion sort algorithm:
Has a quadratic order of growth and is therefore suitable for
sorting small lists only
Is much more efficient than bubble sort, and selection sort, if
the list that needs to be sorted is nearly sorted
Sorting Data by Using Insertion Sort

2. Data Structures and Algorithms
Session 4Ver. 1.0
To understand the implementation of insertion sort
algorithm, consider an unsorted list of numbers stored in an
array.
Implementing Insertion Sort Algorithm
210 43
70 103080 20arr

3. Data Structures and Algorithms
Session 4Ver. 1.0
To sort this list by using the insertion sort algorithm:
You need to divide the list into two sublists, sorted and
unsorted.
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr

4. Data Structures and Algorithms
Session 4Ver. 1.0
To sort this list by using the insertion sort algorithm:
You need to divide the list into two sublists, sorted and
unsorted.
Initially, the sorted list has the first element and the unsorted
list has the remaining 4 elements.
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
0
70 103080 20
21 43

5. Data Structures and Algorithms
Session 4Ver. 1.0
Pass 1
Place the first element from the unsorted list at its correct
position in the sorted list.
Implementing Insertion Sort Algorithm (Contd.)
0
70 103080 20
21 43
Sorted List Unsorted List

6. Data Structures and Algorithms
Session 4Ver. 1.0
Pass 1
Place the first element from the unsorted list at its correct
position in the sorted list.
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
10
70 80
32
30 10 20
4

7. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
10
70 80
32
30 10 20
4
Pass 2
Place the first element from the unsorted list at its correct
position in the sorted list.

8. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
30 70 80 2010
Pass 2
Place the first element from the unsorted list at its correct
position in the sorted list.

9. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
30 70 80 2010
Pass 3
Place the first element from the unsorted list at its correct
position in the sorted list.

10. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
10 10
30 70 80
2
10
3
20
4
Pass 3
Place the first element from the unsorted list at its correct
position in the sorted list.

11. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
10 10
30 70 80
2
10
3
20
4
Pass 4
Place the first element from the unsorted list at its correct
position in the sorted list.

12. Data Structures and Algorithms
Session 4Ver. 1.0
Implementing Insertion Sort Algorithm (Contd.)
Sorted List Unsorted List
210 43
10 703020 80
Pass 4
Place the first element from the unsorted list at its correct
position in the sorted list.

13. Data Structures and Algorithms
Session 4Ver. 1.0
Let us now write an algorithm to
implement insertion sort algorithm.
Implementing Insertion Sort Algorithm (Contd.)
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1
210 43
70 103080 20arr

14. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
Implementing Insertion Sort Algorithm (Contd.)
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1
210 43
70 103080 20arr

15. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

16. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
temp = 80
Implementing Insertion Sort Algorithm (Contd.)
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1
210 43
70 103080 20arr
i

17. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
temp = 80
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

18. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
temp = 80
arr[j] < temp
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

19. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
temp = 80
arr[j] < temp
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
Value temp is stored at its correct
position in the sorted list
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

20. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 1
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

21. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

22. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

23. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

24. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

25. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

26. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 103080 20arr
ij
80
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

27. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 1080 20arr
ijj
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

28. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
Implementing Insertion Sort Algorithm (Contd.)
210 43
70 1080 20arr
ij
70
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

29. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
j = –1
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr
ij
70
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

30. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
temp = 30
j = –1
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr
i
7030
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

31. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 2
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

32. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

33. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

34. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

35. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

36. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
1080 20arr 7030
ij
80
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

37. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 7030
ijj
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

38. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 7030
ij
70
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

39. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 30
ij
70
j
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

40. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 30
i
70
j
30
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

41. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
j = –1
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr
i
70
j
30
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

42. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
temp = 10
j = –1
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr
i
703010
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

43. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 3
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr
i
703010
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

44. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr
i
703010
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

45. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 703010
i
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

46. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 703010
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

47. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 703010
ij
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

48. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80 20arr 703010
ij
80
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

49. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 703010
ijj
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

50. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 703010
ij
70
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

51. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 3010
ij
70
j
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

52. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 3010
i
70
j
30
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

53. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 10
i
70
j
30
j
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1

54. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
temp = 20
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 10
i
703020
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1
j

55. Data Structures and Algorithms
Session 4Ver. 1.0
n = 5
i = 4
Implementing Insertion Sort Algorithm (Contd.)
210 43
80arr 10
i
703020
The list is now sorted
1. Repeat steps 2, 3, 4, and 5
varying i from 1 to n – 1
2. Set temp = arr[i]
3. Set j = i – 1
4. Repeat until j becomes less
than 0 or arr[j] becomes less
than or equal to temp:
a. Shift the value at index
j to index j + 1
b. Decrement j by 1
5. Store temp at index j + 1
j

56. Data Structures and Algorithms
Session 4Ver. 1.0
public void insertionSort()
{
int out,in;
for(out=1;out<nElems;out++)
{
long temp=a[out];
in=out;
while(in>0 && a[in-1]>=temp])
{
a[in]=a[in-1];
in--;
}
a[in]=temp;
}
}
Insertion Sort Method

57. Data Structures and Algorithms
Session 4Ver. 1.0
To sort a list of size n by using insertion sort, you need to
perform (n – 1) passes.
Best Case Efficiency:
Best case occurs when the list is already sorted.
In this case, you will have to make only one comparison in
each pass.
In n – 1 passes, you will need to make n – 1 comparisons.
The best case efficiency of insertion sort is of the order O(n).
Worst Case Efficiency:
Worst case occurs when the list is sorted in the reverse order.
In this case, you need to perform one comparison in the first
pass, two comparisons in the second pass, three comparisons
in the third pass, and n – 1 comparisons in the (n – 1)th
pass.
The worst case efficiency of insertion sort is of the order O(n2
).
Determining the Efficiency of Insertion Sort Algorithm

58. Data Structures and Algorithms
Session 4Ver. 1.0
A sales manager has to do a research on best seller cold
drinks in the market for the year 2004-2006. David, the
software developer, has a list of all the cold drink brands
along with their sales figures stored in a file. David has to
provide the sorted data to the sales manager. The data in
the file is more or less sorted. Which sorting algorithm will
be most efficient for sorting this data and why?
Just a minute
Answer:
Insertion sort provides better efficiency than bubble sort and
selection sort when the list is partially sorted. Therefore, David
should use the insertion sort algorithm.