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C++ Programming: From Problem Analysis to Program Design, Fifth Edition

C++ Programming: From Problem Analysis to Program Design, Fifth Edition. Chapter 10: Applications of Arrays and the class vector. Objectives. In this chapter, you will:

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C++ Programming: From Problem Analysis to Program Design, Fifth Edition

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  1. C++ Programming: From Problem Analysis to Program Design, Fifth Edition Chapter 10: Applications of Arrays and the class vector

  2. Objectives In this chapter, you will: • Explore how to sort an array using the bubble sort, selection sort, and insertion sort algorithms • Learn how to implement the binary search algorithm • Become familiar with the vector type C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  3. List Processing • List: a collection of values of the same type • Basic list operations: • Search the list for a given item • Sort the list • Insert an item in the list • Delete an item from the list • Print the list C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  4. Searching • Sequential search algorithm C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  5. Searching (cont'd.) • List with 1000 elements • Search item is the second item • Sequential search makes two key comparisons • Search item is the 900th item • Sequential search makes 900 key comparisons • Search item is not in the list • Sequential search makes 1000 key comparisons C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  6. Searching (cont'd.) • Sequential search • Not very efficient for large lists • On average, number of key comparisons equal to half the size of the list • Does not assume that the list is sorted C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  7. Bubble Sort • list[0]...list[n - 1] • List of n elements, indexed 0 to n - 1 C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  8. Bubble Sort (cont'd.) • Series of n - 1 iterations • Successive elements list[index] and list[index + 1] of list are compared • If list[index]>list[index + 1] • Elements list[index] and list[index + 1] are swapped • Smaller elements move toward the top • Larger elements move toward the bottom C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  9. Bubble Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  10. Bubble Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  11. Bubble Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  12. Bubble Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  13. Bubble Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  14. Bubble Sort (cont'd.) • List of length n • Exactly n(n - 1) / 2 key comparisons • On average n(n - 1) / 4 item assignments • n = 1000 • 500,000 key comparisons • 250,000 item assignments C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  15. Selection Sort • Rearrange the list by selecting an element in the list and moving it to its proper position • Finds the location of the smallest element in the unsorted portion of the list • Moves it to the top of the unsorted portion of the list C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  16. Selection Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  17. Selection Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  18. Selection Sort (cont'd.) • In the unsorted portion of the list: • Find the location of the smallest element • Move the smallest element to the beginning of the unsorted list C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  19. Selection Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  20. Selection Sort (cont'd.) • List of length n • Exactly n(n - 1) / 2key comparisons • 3(n - 1) item assignments • n = 1000 • 500,000 key comparisons • 3000 item assignments C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  21. Insertion Sort • Sorts the list by moving each element to its proper place C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  22. Insertion Sort (cont'd.) • Consider the element list[4] • First element of unsorted list • list[4] < list[3] • Move list[4] to proper location • At list[2] C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  23. Insertion Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  24. Insertion Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  25. Insertion Sort (cont'd.) • During the sorting phase • Array containing the list is divided into two sublists: sorted and unsorted C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  26. Insertion Sort (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  27. Insertion Sort (cont'd.) • List of length n • About (n2 + 3n – 4) / 4 key comparisons • About n(n – 1) / 4 item assignments • n = 1000 • 250,000 key comparisons • 250,000 item assignments C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  28. Binary Search • Much faster than a sequential search • List must be sorted • “Divide and conquer” • Compare search item with middle element • Less than middle: search only upper half of list • More than middle: search only lower half of list C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  29. Binary Search (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  30. Binary Search (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  31. Binary Search (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  32. Performance of Binary Search • L is a sorted list of size 1024 • Every iteration of the while loop cuts the size of the search list by half • At most, 11 iterations to determine whether x is in L • Binary search will make 22 comparisons at most • L has1048576 elements • Binary search makes 42 item comparisons at most C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  33. Performance of Binary Search (cont'd.) • List of length n • Maximum number comparisons 2log2n + 2 C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  34. vector type (class) • Only a fixed number of elements can be stored in an array • Inserting and removing elements causes shifting • vector type implements a list • vector container • vector • vector object • object C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  35. vector type (class) (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  36. vector type (class) (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  37. vector type (class) (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  38. vector type (class) (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  39. Programming Example: Election Results • Presidential election for the student council of your local university • Write a program to analyze the data and report the winner • Four major divisions labeled as Region 1, Region 2, Region 3, and Region 4 • Each division has several department • Each department manages its own voting process and directly reports the results to the election committee C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  40. Programming Example: Election Results (cont'd.) • Desired output: • Voting is reported in the following form: C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  41. Programming Example: Election Results (cont'd.) • Assume that six candidates are running • Program can be modified to accommodate any number of candidates • Data is provided in two files: • candData.txt consists of the names of candidates • voteData.txt each line consists of voting results • One entry per line C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  42. Programming Example: Input and Output • Input: Two files, one containing the candidates’ names and the other containing the voting data • Output: election results in a tabular form and the winner C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  43. Programming Example: Problem Analysis • Program must organize the voting data by region • Program must calculate total number of votes received by each candidate as well as the total votes cast in the election • Names of the candidates must appear in alphabetical order C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  44. Programming Example: Problem Analysis (cont'd.) • Data type of a candidate’s name and number of votes are different • Separate arrays • Use a two-dimensional array to hold the next four columns of the output • One-dimensional array to hold the total votes received by each candidate C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  45. Programming Example: Problem Analysis (cont'd.) C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  46. Programming Example: Algorithm Design • Read the candidates’ names into the array candidatesName • Sort the array candidatesName • Initialize the arrays votesByRegion and totalVotes • Process the voting data • Calculate the total votes received by each candidate • Output the results C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  47. Programming Example: Function getCandidatesName() C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  48. Programming Example: Function sortCandidateName() C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  49. Programming Example: Function initialize() C++ Programming: From Problem Analysis to Program Design, Fifth Edition

  50. Programming Example: Process Voting Data • Get a candidateName, regionNumber, and numberOfVotesForTheCandidate • Find the row number in the array candidatesName that corresponds to this candidate • This gives the corresponding row number in the array votesByRegion for this candidate • Find the column in the array votesByRegion that corresponds to the regionNumber C++ Programming: From Problem Analysis to Program Design, Fifth Edition

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