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Algorithms Lecture 4: Sorting Algorithms I

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Sorting Algorithms, Bubble Sort, Selection Sort, Insertion Sort

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Algorithms Lecture 4: Sorting Algorithms I

  1. 1. Analysis and Design of Algorithms Sorting Algorithms I
  2. 2. Analysis and Design of Algorithms Sorting Algorithms Bubble Sort Selection Sort Insertion Sort
  3. 3. Analysis and Design of Algorithms  Sorting Algorithm is an algorithm made up of a series of instructions that takes an array as input, and outputs a sorted array.  There are many sorting algorithms, such as:  Selection Sort, Bubble Sort, Insertion Sort, Merge Sort, Heap Sort, QuickSort, Radix Sort, Counting Sort, Bucket Sort, ShellSort, Comb Sort, Pigeonhole Sort, Cycle Sort
  4. 4. Analysis and Design of Algorithms Bubble Sort
  5. 5. Analysis and Design of Algorithms Bubble Sort is the simplest sorting algorithm that works by repeatedly swapping the adjacent elements if they are in wrong order.
  6. 6. Analysis and Design of Algorithms Algorithm:  Step1: Compare each pair of adjacent elements in the list  Step2: Swap two element if necessary  Step3: Repeat this process for all the elements until the entire array is sorted
  7. 7. Analysis and Design of Algorithms  Example 1 Assume the following Array: 5 1 4 2
  8. 8. Analysis and Design of Algorithms  First Iteration:  Compare 5 1 4 2  j  j+1
  9. 9. Analysis and Design of Algorithms  First Iteration:  Swap 1 5 4 2  j  j+1
  10. 10. Analysis and Design of Algorithms  First Iteration:  Compare 1 5 4 2  j  j+1
  11. 11. Analysis and Design of Algorithms  First Iteration:  Swap 1 4 5 2  j  j+1
  12. 12. Analysis and Design of Algorithms  First Iteration:  Compare 1 4 5 2  j  j+1
  13. 13. Analysis and Design of Algorithms  First Iteration:  Swap 1 4 2 5  j  j+1
  14. 14. Analysis and Design of Algorithms 1 4 2 5
  15. 15. Analysis and Design of Algorithms  Second Iteration:  Compare 1 4 2 5  j  j+1
  16. 16. Analysis and Design of Algorithms  Second Iteration:  Compare 1 4 2 5  j  j+1
  17. 17. Analysis and Design of Algorithms  Second Iteration:  Swap 1 2 4 5  j  j+1
  18. 18. Analysis and Design of Algorithms 1 2 4 5
  19. 19. Analysis and Design of Algorithms  Third Iteration:  Compare 1 2 4 5  j  j+1
  20. 20. Analysis and Design of Algorithms 1 2 4 5
  21. 21. Analysis and Design of Algorithms  Array is now sorted 1 2 3 4
  22. 22. Analysis and Design of Algorithms 5 4 2 1 3 4 5 2 1 3 4 2 5 1 3 4 2 1 5 3 4 2 1 3 5 4 2 1 3 5 2 4 1 3 5 2 1 4 3 5 2 1 3 4 5 2 1 3 4 5 1 2 3 4 5 1 2 3 4 5  Example 2:
  23. 23. Analysis and Design of Algorithms  What is the output of bubble sort after the 1st iteration given the following sequence of numbers: 13 2 9 4 18 45 37 63 a) 2 4 9 13 18 37 45 63 b) 2 9 4 13 18 37 45 63 c) 13 2 4 9 18 45 37 63 d) 2 4 9 13 18 45 37 63
  24. 24. Analysis and Design of Algorithms  What is the output of bubble sort after the 1st iteration given the following sequence of numbers: 13 2 9 4 18 45 37 63 a) 2 4 9 13 18 37 45 63 b) 2 9 4 13 18 37 45 63 c) 13 2 4 9 18 45 37 63 d) 2 4 9 13 18 45 37 63
  25. 25. Analysis and Design of Algorithms  Python Code
  26. 26. Analysis and Design of Algorithms
  27. 27. Analysis and Design of Algorithms  Time Complexity: O(n2) as there are two nested loops  Example of worst case 5 4 3 2 1
  28. 28. Analysis and Design of Algorithms Selection Sort
  29. 29. Analysis and Design of Algorithms The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning.
  30. 30. Analysis and Design of Algorithms Algorithm:  Step1: Find the minimum value in the list  Step2: Swap it with the value in the current position  Step3: Repeat this process for all the elements until the entire array is sorted
  31. 31. Analysis and Design of Algorithms  Example 1 Assume the following Array: 8 12 5 9 2
  32. 32. Analysis and Design of Algorithms  Compare 8 12 5 9 2  i  j  min
  33. 33. Analysis and Design of Algorithms  Compare 8 12 5 9 2  i  j  min
  34. 34. Analysis and Design of Algorithms  Move 8 12 5 9 2  j  i  min
  35. 35. Analysis and Design of Algorithms  Compare 8 12 5 9 2  i  min  j
  36. 36. Analysis and Design of Algorithms  Compare 8 12 5 9 2  i  min  j
  37. 37. Analysis and Design of Algorithms  Move 8 12 5 9 2  i  j  min
  38. 38. Analysis and Design of Algorithms  Smallest 8 12 5 9 2  i  min
  39. 39. Analysis and Design of Algorithms  Swap 8 12 5 9 2  min  i
  40. 40. Analysis and Design of Algorithms  Sorted  Un Sorted 2 12 5 9 8  Sorted  Un Sorted
  41. 41. Analysis and Design of Algorithms  Compare 2 12 5 9 8  i  min  j  Sorted
  42. 42. Analysis and Design of Algorithms  Move 2 12 5 9 8  i  min  j  Sorted
  43. 43. Analysis and Design of Algorithms  Compare 2 12 5 9 8  Sorted  i  j  min
  44. 44. Analysis and Design of Algorithms  Compare 2 12 5 9 8  Sorted  i  j  min
  45. 45. Analysis and Design of Algorithms  Smallest 2 12 5 9 8  Sorted  i  min
  46. 46. Analysis and Design of Algorithms  Swap 2 12 5 9 8  Sorted  i  min
  47. 47. Analysis and Design of Algorithms  Sorted  Un Sorted 2 5 12 9 8  Sorted  Un Sorted
  48. 48. Analysis and Design of Algorithms  Compare 2 5 12 9 8  Sorted  i  j  min
  49. 49. Analysis and Design of Algorithms  Move 2 5 12 9 8  Sorted  i  j  min
  50. 50. Analysis and Design of Algorithms  Compare 2 5 12 9 8  Sorted  i  min  j
  51. 51. Analysis and Design of Algorithms  Move 2 5 12 9 8  Sorted  i  min  j
  52. 52. Analysis and Design of Algorithms  Smallest 2 5 12 9 8  Sorted  i  min
  53. 53. Analysis and Design of Algorithms  Swap 2 5 12 9 8  Sorted  i  min
  54. 54. Analysis and Design of Algorithms  Sorted  Un Sorted 2 5 8 9 12  Sorted  Un Sorted
  55. 55. Analysis and Design of Algorithms  Compare 2 5 8 9 12  Sorted  i  min  j
  56. 56. Analysis and Design of Algorithms  Sorted  Un Sorted 2 5 8 9 12  Sorted  Un Sorted
  57. 57. Analysis and Design of Algorithms  Sorted  Un Sorted 2 5 8 9 12  Sorted  i  min
  58. 58. Analysis and Design of Algorithms  Array is now sorted 2 5 8 9 12  Sorted
  59. 59. Analysis and Design of Algorithms 12 10 16 11 9 7 Example 2: 7 10 16 11 9 12 7 9 16 11 10 12 7 9 10 11 16 12 7 9 10 11 16 12 7 9 10 11 12 16 12 10 16 11 9 7
  60. 60. Analysis and Design of Algorithms  What is the output of selection sort after the 2nd iteration given the following sequence of numbers: 13 2 9 4 18 45 37 63 a) 2 4 9 13 18 37 45 63 b) 2 9 4 13 18 37 45 63 c) 13 2 4 9 18 45 37 63 d) 2 4 9 13 18 45 37 63
  61. 61. Analysis and Design of Algorithms  What is the output of selection sort after the 2nd iteration given the following sequence of numbers: 13 2 9 4 18 45 37 63 a) 2 4 9 13 18 37 45 63 b) 2 9 4 13 18 37 45 63 c) 13 2 4 9 18 45 37 63 d) 2 4 9 13 18 45 37 63
  62. 62. Analysis and Design of Algorithms  Python Code
  63. 63. Analysis and Design of Algorithms
  64. 64. Analysis and Design of Algorithms  Time Complexity: O(n2) as there are two nested loops  Example of worst case 2 3 4 5 1
  65. 65. Analysis and Design of Algorithms Insertion Sort
  66. 66. Analysis and Design of Algorithms Insertion sort is a simple sorting algorithm that works the way we sort playing cards in our hands.
  67. 67. Analysis and Design of Algorithms  Algorithm:  Step1: Compare each pair of adjacent elements in the list  Step2: Insert element into the sorted list, until it occupies correct position.  Step3: Swap two element if necessary  Step4: Repeat this process for all the elements until the entire array is sorted
  68. 68. Analysis and Design of Algorithms  Assume the following Array: 5 1 4 2
  69. 69. Analysis and Design of Algorithms  Compare  Store= 5 1 4 2  i  j  j+1 1
  70. 70. Analysis and Design of Algorithms  Move  Store= 5 4 2  i  j  j+1 1
  71. 71. Analysis and Design of Algorithms  Move  Store= 1 5 4 2  i  j+1
  72. 72. Analysis and Design of Algorithms  Compare  Store= 1 5 4 2  i  j 4  j+1
  73. 73. Analysis and Design of Algorithms  Move  Store= 1 5 2  i  j 4  j+1
  74. 74. Analysis and Design of Algorithms  Compare  Store= 1 5 2  i  j 4  j+1
  75. 75. Analysis and Design of Algorithms  Move  Store= 1 4 5 2  i  j  j+1
  76. 76. Analysis and Design of Algorithms  Compare  Store= 1 4 5 2  i  j 2  j+1
  77. 77. Analysis and Design of Algorithms  Move  Store= 1 4 5  i  j 2  j+1
  78. 78. Analysis and Design of Algorithms  Compare  Store= 1 4 5  i  j 2  j+1
  79. 79. Analysis and Design of Algorithms  Move  Store= 1 4 5  i  j 2  j+1
  80. 80. Analysis and Design of Algorithms  Compare  Store= 1 4 5  i  j 2  j+1
  81. 81. Analysis and Design of Algorithms  Compare  Store= 1 2 4 5  i  j  j+1
  82. 82. Analysis and Design of Algorithms  Array is now sorted 1 2 4 5
  83. 83. Analysis and Design of Algorithms 5 1 8 3 9 2  Example 2: 1 5 8 3 9 2 1 5 8 3 9 2 1 3 5 8 9 2 1 3 5 8 9 2 1 2 3 5 8 9 5 1 8 3 9 2
  84. 84. Analysis and Design of Algorithms  What is the output of insertion sort after the 1st iteration given the following sequence of numbers: 7 3 5 1 9 8 4 6 a) 3 7 5 1 9 8 4 6 b) 1 3 7 5 9 8 4 6 c) 3 4 1 5 6 8 7 9 d) 1 3 4 5 6 7 8 9
  85. 85. Analysis and Design of Algorithms  What is the output of insertion sort after the 1st iteration given the following sequence of numbers: 7 3 5 1 9 8 4 6 a) 3 7 5 1 9 8 4 6 b) 1 3 7 5 9 8 4 6 c) 3 4 1 5 6 8 7 9 d) 1 3 4 5 6 7 8 9
  86. 86. Analysis and Design of Algorithms  What is the output of insertion sort after the 2nd iteration given the following sequence of numbers: 7 3 5 1 9 8 4 6 a) 3 5 7 1 9 8 4 6 b) 1 3 7 5 9 8 4 6 c) 3 4 1 5 6 8 7 9 d) 1 3 4 5 6 7 8 9
  87. 87. Analysis and Design of Algorithms  What is the output of insertion sort after the 2nd iteration given the following sequence of numbers: 7 3 5 1 9 8 4 6 a) 3 5 7 1 9 8 4 6 b) 1 3 7 5 9 8 4 6 c) 3 4 1 5 6 8 7 9 d) 1 3 4 5 6 7 8 9
  88. 88. Analysis and Design of Algorithms  Python Code
  89. 89. Analysis and Design of Algorithms
  90. 90. Analysis and Design of Algorithms  Time Complexity: O(n2)  Example of worst case 5 4 3 2 1
  91. 91. Analysis and Design of Algorithms facebook.com/mloey mohamedloey@gmail.com twitter.com/mloey linkedin.com/in/mloey mloey@fci.bu.edu.eg mloey.github.io
  92. 92. Analysis and Design of Algorithms www.YourCompany.com © 2020 Companyname PowerPoint Business Theme. All Rights Reserved. THANKS FOR YOUR TIME

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