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Chapter 10

Chapter 10. Applications of Arrays and Strings. Chapter Objectives. Learn how to implement the sequential search algorithm Explore how to sort an array using the selection sort algorithm Learn how to implement the binary search algorithm Become aware of the class Vector

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Chapter 10

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  1. Chapter 10 Applications of Arrays and Strings

  2. Chapter Objectives • Learn how to implement the sequential search algorithm • Explore how to sort an array using the selection sort algorithm • Learn how to implement the binary search algorithm • Become aware of the class Vector • Learn more about manipulating strings using the class String

  3. List Processing • List: a set of values of the same type • Basic operations performed on a list: • Search list for given item • Sort list • Insert item in list • Delete item from list

  4. Search • Necessary components to search a list: • Array containing the list • Length of the list • Item for which you are searching • After search completed: • If item found, report “success”, return location in array • If item not found, report “failure”

  5. Search

  6. Sorting a List • Selection sort • Sorting algorithm • List is sorted by selecting list element and moving it to its proper position • Algorithm finds position of smallest element and moves it to top of unsorted portion of list • Repeats process above until entire list is sorted

  7. Selection Sort

  8. Sequential Ordered Search

  9. Binary Search • Can only be performed on a sorted list • Uses divide and conquer technique to search list • If L is a sorted list of size n, to determine whether an element is in L, the binary search makes at most 2 * log2n + 2 key comparisons • (Faster than a sequential search)

  10. Binary Search Algorithm • Search item is compared with middle element of list • If search item < middle element of list, search is restricted to first half of the list • If search item > middle element of list, search second half of the list • If search item = middle element, search is complete

  11. Binary Search

  12. Vectors • The class Vector can be used to implement a list • Unlike an array, the size of a Vector object can grow/shrink during program execution • You do not need to worry about the number of data elements in vector

  13. Members of the class Vector

  14. Methods of the class Vector

  15. Methods of the class Vector

  16. Methods of the class Vector

  17. Vectors • Every element of a Vector object is a reference variable of the type Object • To add an element into a Vector object • Create appropriate object • Store data into object • Store address of object holding data into Vector object element

  18. Vector StringList: After Adding Four Strings

  19. Programming Example: Election Results • Input: two files • File 1: candidates’ names • File 2: voting data • Voting Data Format: • candidate_name region# number_of_votes_for_this_candidate

  20. Programming Example: Election Results • Output: election results in a tabular form • each candidate’s name • number of votes each candidate received in each region • total number of votes each candidate received

  21. Programming Example:Election Results (Solution) The solution includes: • Reading the candidates’ names into the array candidateName • A two-dimensional array consisting of the votes by Region • An array consisting of the total votes parallel to the candidateName array

  22. Programming Example:Election Results (Solution) • Sorting the array candidatesName • Processing the voting data • Calculating the total votes received by each candidate • Outputting the results in tabular form

  23. Programming Example: Election Results

  24. Programming Example: Election Results

  25. Additional String Methods

  26. Additional String Methods

  27. Additional String Methods

  28. Additional String Methods

  29. Effects of some String Methods

  30. Programming Example: Pig Latin Strings • If string begins with a vowel “-way” is appended to it • If first character is not a vowel • Add “-” to end • Rotate characters until the first character is a vowel • Append “ay” • Input: string • Output: string in pig Latin

  31. Programming Example: Pig Latin Strings (Solution) • Methods: isVowel, rotate, pigLatinString • Use methods to: • Get the string (str) • Find the pig Latin form of str by using the method pigLatinString • Output the pig Latin form of str

  32. Programming Example: Pig Latin Strings (Sample Runs)

  33. Chapter Summary • Lists • Searching lists • Sequential searching order • Binary Search • Sorting lists • Selection sort

  34. Chapter Summary • Programming examples • The class Vector • Members of the class Vector • The class String • Additional methods of the class String

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