2第9章课件.docVIP

Java Software Solutions: Foundations of Program Design, 6e (Lewis/Loftus) Chapter 9 Polymorphism Multiple-Choice Questions 1) What does the following code do? Assume list is an array of int values, temp is some previously initialized int value, and c is an int initialized to 0. for (j=0; j list.length; j++) if (list[j] temp) c++; A) It finds the smallest value and stores it in temp B) It finds the largest value and stores it in temp C) It counts the number of elements equal to the smallest value in list D) It counts the number of elements in list that are less than temp E) It sorts the values in list to be in ascending order Answer: D Explanation: D) The statement if (list[j] temp) c++; compares each element in list to temp and adds one to c only if the element is less than temp, so it counts the number of elements in list less than temp, storing this result in c. An int array stores the following values. Use the array to answer these next questions. 2) Which of the following lists of numbers would accurately show the array after the first pass through the Selection Sort algorithm? A) 9, 4, 12, 2, 6, 8, 18 B) 4, 9, 12, 2, 6, 8, 18 C) 2, 4, 12, 9, 6, 8, 18 D) 2, 4, 6, 8, 9, 12, 18 E) 2, 4, 9, 12, 6, 8, 18 Answer: C Explanation: C) On each successive pass of Selection Sort, the smallest of the unsorted values is found and swapped with the current array index (where the current index starts at 0 and goes until the second to last position in the array). On the first pass, the smallest element, 2, is swapped with index 0, so 2 and 9 swap places. 3) Which of the following lists of numbers would accurately show the array after the second pass of the Selection Sort algorithm? A) 9, 4, 12, 2, 6, 8, 18 B) 2, 4, 9, 6, 12, 8, 18 C) 2, 4, 12, 9, 6, 8, 18 D) 2, 4, 6, 8, 9, 12, 18 E) 2, 4, 12, 6, 8, 9, 18 Answer: C Explanation: C) After one pass, the array would be 2, 4, 12, 9, 6, 8, 18. The second pass would look to swap the item in array