Question 1

Assume we are using quicksort to sort an array in ascending order. Into which array location does quicksort's strategy place a pivot element after partitioning?

Accepted Answer

A)  lowest index in array still available 
B)  highest index in array still available 
C)  closer to its correct final location 
D)  its final correct location 
A)  lowest index in array still available 
B)  highest index in array still available 
C)  closer to its correct final location 
D)  its final correct location D

Question 2

In the textbook, we found that the number of element visits for merge sort totaled n + 5nlog2n. Let's consider sorting 1024 elements. How many visits are needed?

Accepted Answer

A)  1.024 
B)  6,144 
C)  51,200 
D)  52,224 
A)  1.024 
B)  6,144 
C)  51,200 
D)  52,224 D

Question 3

Suppose objects a and b are from a user-defined class that implements the Comparable interface. What must be true about the return value of a.compareTo(b) for the compareTo method that this class implements?

Accepted Answer

A)  It must return 1 if a comes before b, 0 if they are the same, and -1 if a comes after b. 
B)  It must return -1 if a comes before b, 0 if they are the same, and 1 if a comes after b. 
C)  It must return a positive value if a comes before b, 0 if they are the same, and a negative value if a comes after b. 
D)  It must return a negative value if a comes before b, 0 if they are the same, and a positive value if a comes after b. 
A)  It must return 1 if a comes before b, 0 if they are the same, and -1 if a comes after b. 
B)  It must return -1 if a comes before b, 0 if they are the same, and 1 if a comes after b. 
C)  It must return a positive value if a comes before b, 0 if they are the same, and a negative value if a comes after b. 
D)  It must return a negative value if a comes before b, 0 if they are the same, and a positive value if a comes after b. D

Question 4

Given the following code snippet for searching an array:
Int[] arr = {23, 25, 29, 34, 42};
Int newVal = 15;
Int pos = Arrays.binarySearch(arr, newVal);
What value will pos have when this code is executed?

Accepted Answer

A)  0 
B)  1 
C)  -1 
D)  -2 
A)  0 
B)  1 
C)  -1 
D)  -2

Question 5

The partial linear search method below is designed to search an array of String objects. Select the expression that would be needed to complete the method. public static int search(String[] a, String item)
{
For (int i = 0; i < a.length; i++)
{
If ( ____________________________ )
{
Return i;
}
Return -1;
}
}

Accepted Answer

A)  a[i] == item 
B)  a[i].compareTo(item) 
C)  a[i].equals(item) 
D)  a[i].indexOf(item) 
A)  a[i] == item 
B)  a[i].compareTo(item) 
C)  a[i].equals(item) 
D)  a[i].indexOf(item)

Question 6

Complete the following code that is intended to provide a comparator interface that will be used to create an object that implements the Comparator interface so that object can compare Auto objects. ___________________________
{
Int compare(Auto a, Auto B); }

Accepted Answer

A) public class Comparator B) public class Comparator implements Comparator C) public interface Auto D) public interface Comparator A) public class Comparator B) public class Comparator implements Comparator C) public interface Auto D) public interface Comparator

Question 7

The performance of an algorithm is most closely related to what?

Accepted Answer

A)  The total number of element visits 
B)  The total number of elements 
C)  The type of elements 
D)  The number of lines of code in the method 
A)  The total number of element visits 
B)  The total number of elements 
C)  The type of elements 
D)  The number of lines of code in the method

Question 8

Which of the following statements about running times of algorithms is correct?

Accepted Answer

A)  An algorithm that is O(1) means that only one comparison takes place. 
B)  When determining the running time, constants are not taken into consideration. 
C)  When determining the running time, lower-order terms must be taken into consideration. 
D)  An algorithm that is O(n) means that the number of comparisons does not grow as the size of the array increases. 
A)  An algorithm that is O(1) means that only one comparison takes place. 
B)  When determining the running time, constants are not taken into consideration. 
C)  When determining the running time, lower-order terms must be taken into consideration. 
D)  An algorithm that is O(n) means that the number of comparisons does not grow as the size of the array increases.

Question 9

In Big-Oh notation, selection sort is a(n) ____ algorithm.

Accepted Answer

A)  O(n2) 
B)  O(1) 
C)  log n 
D)  O(log n2) 
A)  O(n2) 
B)  O(1) 
C)  log n 
D)  O(log n2)

Question 10

The largestPosition method below returns the index of the largest element in the tail range of an array of integers. Select the expression that would be needed to complete the selectionSort method below, so that it sorts the elements in descending order. /**
Finds the largest element in the tail range of an array.
@param a the array to be searched
@param from the first position in a to compare
@return the position of the largest element in range a[from]..a[a.length - 1]
*/
Private static int largestPosition(int[] a, int from)
{
Int maxPos = from;
For (int j = from + 1; j  a[maxPos])
{
MaxPos = j;
}
}
Return maxPos;
}
Public static void selectionSort(int[]A) (int i = 0; i < a.length - 1; i++)

Accepted Answer

A)  {
For ____________________________________
{
Int maxPos = largestPosition(a, i);
ArrayUtil.swap(a, maxPos, i);
}
} 
B)  (int i = 0; i  0; i--) 
D)  (int i = a.length - 1; i > 0; i--) 
A)  {
For ____________________________________
{
Int maxPos = largestPosition(a, i);
ArrayUtil.swap(a, maxPos, i);
}
} 
B)  (int i = 0; i  0; i--) 
D)  (int i = a.length - 1; i > 0; i--)

Question 11

Which of the following classes implement the Comparable interface?
I Date
II Collections
III String

Accepted Answer

A)  I 
B)  I and II 
C)  I and III 
D)  II and III 
A)  I 
B)  I and II 
C)  I and III 
D)  II and III

Question 12

Suppose you wish to implement the Comparable interface to allow your Vehicle class to compare Auto objects only. Which of the following is the correct way to do this?

Accepted Answer

A) public class Auto implements Comparable B) public class Vehicle implements Comparable C) public class Vehicle implements Comparable D) public class Vehicle implements Comparable(Auto) A) public class Auto implements Comparable B) public class Vehicle implements Comparable C) public class Vehicle implements Comparable D) public class Vehicle implements Comparable(Auto)

Question 13

The following code is an example of a ___ search. public static int search(int[] a, int v)
{
For (int i = 0; i < a.length; i++)
{
If (a[i] == v) { return i; }
}
Return -1;
}

Accepted Answer

A)  sorted 
B)  binary 
C)  linear 
D)  random 
A)  sorted 
B)  binary 
C)  linear 
D)  random

Question 14

In general, the expression ____ means that f grows no faster than g.

Accepted Answer

A)  f(n) = log g 
B)  f(n) = log g2 
C)  f(n) = O(g(n)) 
D)  g(n) = O(f(n)) 
A)  f(n) = log g 
B)  f(n) = log g2 
C)  f(n) = O(g(n)) 
D)  g(n) = O(f(n))

Question 15

A portion of your program includes the method shown in the code snippet below to examine the elements of an array arr: private int findElement(int[] arr, int newVal)
{
Int pos = Arrays.binarySearch(arr, newVal);
Return pos;
}
What can you conclude about the running time of this section of code?

Accepted Answer

A)  Its running time will be O(n). 
B)  Its running time will be O(n2). 
C)  Its running time will be O(log (n)). 
D)  Its running time will be O(n log (n)). 
A)  Its running time will be O(n). 
B)  Its running time will be O(n2). 
C)  Its running time will be O(log (n)). 
D)  Its running time will be O(n log (n)).

Question 16

The ____ class contains a sort method that can sort array lists.

Accepted Answer

A)  Sorting 
B)  Arrays 
C)  Collections 
D)  Linear 
A)  Sorting 
B)  Arrays 
C)  Collections 
D)  Linear

Question 17

How many times can an array with 4,096 elements be cut into two equal pieces?

Accepted Answer

A)  16 
B)  12 
C)  10 
D)  8 
A)  16 
B)  12 
C)  10 
D)  8

Question 18

When does quicksort's worst-case run-time behavior occur?
I when the data is randomly initialized in the array
II when the data is in ascending order
III when the data is in descending order

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  II and III 
A)  I 
B)  II 
C)  III 
D)  II and III

Question 19

Assume that names is an array of String objects that has been initialized with a large number of elements. Select the statement that would sort the elements in names in ascending alphabetic order.

Accepted Answer

A)  Arrays.sort(names, 0, names.length - 1); 
B)  Arrays.sort(names); 
C)  Collections.sort(names, 0, names.length - 1); 
D)  Collections.sort(names); 
A)  Arrays.sort(names, 0, names.length - 1); 
B)  Arrays.sort(names); 
C)  Collections.sort(names, 0, names.length - 1); 
D)  Collections.sort(names);

Question 20

Which of the sorts in the textbook can be characterized by the fact that even in the worst case the running time will be O(n log(n)))?
I quicksort
II selection sort
III merge sort

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  I and III 
A)  I 
B)  II 
C)  III 
D)  I and III

Exam 14: Sorting and Searching

Assume we are using quicksort to sort an array in ascending order. Into which array location does quicksort's strategy place a pivot element after partitioning?

In the textbook, we found that the number of element visits for merge sort totaled n + 5nlog2n. Let's consider sorting 1024 elements. How many visits are needed?

Suppose objects a and b are from a user-defined class that implements the Comparable interface. What must be true about the return value of a.compareTo(b) for the compareTo method that this class implements?

Given the following code snippet for searching an array: Int[] arr = {23, 25, 29, 34, 42}; Int newVal = 15; Int pos = Arrays.binarySearch(arr, newVal); What value will pos have when this code is executed?

Complete the following code that is intended to provide a comparator interface that will be used to create an object that implements the Comparator interface so that object can compare Auto objects. ___________________________ { Int compare(Auto a, Auto B); }

The performance of an algorithm is most closely related to what?

Which of the following statements about running times of algorithms is correct?

In Big-Oh notation, selection sort is a(n) ____ algorithm.

Which of the following classes implement the Comparable interface? I Date II Collections III String

Suppose you wish to implement the Comparable interface to allow your Vehicle class to compare Auto objects only. Which of the following is the correct way to do this?

The following code is an example of a ___ search. public static int search(int[] a, int v) { For (int i = 0; i < a.length; i++) { If (a[i] == v) { return i; } } Return -1; }

In general, the expression ____ means that f grows no faster than g.

A portion of your program includes the method shown in the code snippet below to examine the elements of an array arr: private int findElement(int[] arr, int newVal) { Int pos = Arrays.binarySearch(arr, newVal); Return pos; } What can you conclude about the running time of this section of code?

The ____ class contains a sort method that can sort array lists.

How many times can an array with 4,096 elements be cut into two equal pieces?

When does quicksort's worst-case run-time behavior occur? I when the data is randomly initialized in the array II when the data is in ascending order III when the data is in descending order

Assume that names is an array of String objects that has been initialized with a large number of elements. Select the statement that would sort the elements in names in ascending alphabetic order.

Which of the sorts in the textbook can be characterized by the fact that even in the worst case the running time will be O(n log(n)))? I quicksort II selection sort III merge sort

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In the textbook, we found that the number of element visits for merge sort totaled n + 5nlog₂n. Let's consider sorting 1024 elements. How many visits are needed?