WGU C950 Data Structures and Algorithms II: Exam 2 -
Questions with Correct Answers
100 questions
1. The 'n' in Big-O analysis represents:
A. The number of programmers
B. The speed of the CPU
C. A constant
D. The size of the input
Correct Answer: D. The size of the input
Rationale: Input size.
2. Appending to the end of a Python list is:
A. O(n) always
B. O(log n)
C. O(n^2)
D. Amortized O(1)
Correct Answer: D. Amortized O(1)
Rationale: Occasional resize.
3. Checking membership in a Python set has average complexity:
A. O(1)
B. O(n)
C. O(log n)
D. O(n^2)
Correct Answer: A. O(1)
Rationale: Hash-based.
4. An algorithm with O(n log n) complexity is typical of:
A. Linear search
B. Efficient comparison sorts like merge sort
C. Bubble sort
D. Constant-time lookup
Correct Answer: B. Efficient comparison sorts like merge sort
Rationale: Optimal comparison sorting.
5. A program that is O(n^2) may still be acceptable when:
A. Input is huge
B. Real-time constraints exist for millions of items
C. Input sizes are small and remain small
D. Never
Correct Answer: C. Input sizes are small and remain small
Rationale: Practical considerations.
6. If an algorithm is O(n) and takes 2 seconds for n = 1,000, approximately how long for n =
5,000?
A. 5 seconds
B. 25 seconds
C. 2 seconds
D. 10 seconds
Correct Answer: D. 10 seconds
Rationale: Linear scaling.
,7. When simplifying O(3n^2 + 5n + 10), the result is:
A. O(n^2)
B. O(3n^2)
C. O(n)
D. O(5n)
Correct Answer: A. O(n^2)
Rationale: Drop constants and lower-order terms.
8. collections.deque provides O(1) operations at:
A. Both ends
B. The middle only
C. Random indices
D. No positions
Correct Answer: A. Both ends
Rationale: Double-ended queue.
9. Python's '==' operator checks:
A. Value equality
B. Identity
C. Memory address only
D. Type only
Correct Answer: A. Value equality
Rationale: Equality.
10. The heapq module implements:
A. A max-heap only
B. A hash table
C. A linked list
D. A min-heap on top of a list
Correct Answer: D. A min-heap on top of a list
Rationale: Binary heap.
11. Mutable default arguments (e.g., def f(x=[])) can cause bugs because:
A. They are immutable
B. They are deleted
C. They raise errors immediately
D. The same object is reused across calls
Correct Answer: D. The same object is reused across calls
Rationale: Use None instead.
12. A class in Python is:
A. A built-in list
B. A blueprint for creating objects with attributes and methods
C. A loop
D. A module only
Correct Answer: B. A blueprint for creating objects with attributes and methods
Rationale: OOP.
, 13. A Python class attribute differs from an instance attribute because it is:
A. Unique to each instance
B. Private always
C. Shared by all instances
D. Immutable always
Correct Answer: C. Shared by all instances
Rationale: Class-level.
14. A 2D list (list of lists) is a natural way to store:
A. A single integer
B. A string
C. A distance matrix
D. A boolean
Correct Answer: C. A distance matrix
Rationale: Rows and columns.
15. String hashing in Python may vary between runs because of:
A. Hash randomization for security
B. Bugs
C. CPU speed
D. File size
Correct Answer: A. Hash randomization for security
Rationale: PYTHONHASHSEED.
16. A generator in Python:
A. Yields values lazily one at a time
B. Creates all values at once
C. Is a class
D. Sorts data
Correct Answer: A. Yields values lazily one at a time
Rationale: Memory efficient.
17. When a hash table doubles in size, the load factor:
A. Is roughly halved
B. Doubles
C. Stays the same
D. Becomes zero
Correct Answer: A. Is roughly halved
Rationale: Same items, more buckets.
18. Hashing a string key commonly involves:
A. Sorting characters
B. Combining character codes with multiplication and addition
C. Counting vowels only
D. Using the string length only
Correct Answer: B. Combining character codes with multiplication and addition
Rationale: Polynomial rolling hash.
Questions with Correct Answers
100 questions
1. The 'n' in Big-O analysis represents:
A. The number of programmers
B. The speed of the CPU
C. A constant
D. The size of the input
Correct Answer: D. The size of the input
Rationale: Input size.
2. Appending to the end of a Python list is:
A. O(n) always
B. O(log n)
C. O(n^2)
D. Amortized O(1)
Correct Answer: D. Amortized O(1)
Rationale: Occasional resize.
3. Checking membership in a Python set has average complexity:
A. O(1)
B. O(n)
C. O(log n)
D. O(n^2)
Correct Answer: A. O(1)
Rationale: Hash-based.
4. An algorithm with O(n log n) complexity is typical of:
A. Linear search
B. Efficient comparison sorts like merge sort
C. Bubble sort
D. Constant-time lookup
Correct Answer: B. Efficient comparison sorts like merge sort
Rationale: Optimal comparison sorting.
5. A program that is O(n^2) may still be acceptable when:
A. Input is huge
B. Real-time constraints exist for millions of items
C. Input sizes are small and remain small
D. Never
Correct Answer: C. Input sizes are small and remain small
Rationale: Practical considerations.
6. If an algorithm is O(n) and takes 2 seconds for n = 1,000, approximately how long for n =
5,000?
A. 5 seconds
B. 25 seconds
C. 2 seconds
D. 10 seconds
Correct Answer: D. 10 seconds
Rationale: Linear scaling.
,7. When simplifying O(3n^2 + 5n + 10), the result is:
A. O(n^2)
B. O(3n^2)
C. O(n)
D. O(5n)
Correct Answer: A. O(n^2)
Rationale: Drop constants and lower-order terms.
8. collections.deque provides O(1) operations at:
A. Both ends
B. The middle only
C. Random indices
D. No positions
Correct Answer: A. Both ends
Rationale: Double-ended queue.
9. Python's '==' operator checks:
A. Value equality
B. Identity
C. Memory address only
D. Type only
Correct Answer: A. Value equality
Rationale: Equality.
10. The heapq module implements:
A. A max-heap only
B. A hash table
C. A linked list
D. A min-heap on top of a list
Correct Answer: D. A min-heap on top of a list
Rationale: Binary heap.
11. Mutable default arguments (e.g., def f(x=[])) can cause bugs because:
A. They are immutable
B. They are deleted
C. They raise errors immediately
D. The same object is reused across calls
Correct Answer: D. The same object is reused across calls
Rationale: Use None instead.
12. A class in Python is:
A. A built-in list
B. A blueprint for creating objects with attributes and methods
C. A loop
D. A module only
Correct Answer: B. A blueprint for creating objects with attributes and methods
Rationale: OOP.
, 13. A Python class attribute differs from an instance attribute because it is:
A. Unique to each instance
B. Private always
C. Shared by all instances
D. Immutable always
Correct Answer: C. Shared by all instances
Rationale: Class-level.
14. A 2D list (list of lists) is a natural way to store:
A. A single integer
B. A string
C. A distance matrix
D. A boolean
Correct Answer: C. A distance matrix
Rationale: Rows and columns.
15. String hashing in Python may vary between runs because of:
A. Hash randomization for security
B. Bugs
C. CPU speed
D. File size
Correct Answer: A. Hash randomization for security
Rationale: PYTHONHASHSEED.
16. A generator in Python:
A. Yields values lazily one at a time
B. Creates all values at once
C. Is a class
D. Sorts data
Correct Answer: A. Yields values lazily one at a time
Rationale: Memory efficient.
17. When a hash table doubles in size, the load factor:
A. Is roughly halved
B. Doubles
C. Stays the same
D. Becomes zero
Correct Answer: A. Is roughly halved
Rationale: Same items, more buckets.
18. Hashing a string key commonly involves:
A. Sorting characters
B. Combining character codes with multiplication and addition
C. Counting vowels only
D. Using the string length only
Correct Answer: B. Combining character codes with multiplication and addition
Rationale: Polynomial rolling hash.
