Data Types — Test 4

Correct Answer: D. Yes, guaranteed by the language since Python 3.7
Explanation: Insertion order was an implementation detail in CPython 3.6 and became part of the language in 3.7.

Correct Answer: A. Yes, because it is immutable and hashable
Explanation: A plain set is unhashable. A frozenset is hashable.

Correct Answer: A. It is usually True because of small-integer caching, but that is an implementation detail; use == to compare values
Explanation: CPython caches the integers from -5 to 256. Never rely on is to compare numbers or strings.

Correct Answer: A. False
Explanation: None is falsy, but it is not equal to False. bool(None) is False.

Correct Answer: D. Dynamically and weakly typed
Explanation: JavaScript performs implicit coercions such as "5" - 2 = 3, which makes it weakly typed. Its types are checked at run time.

Correct Answer: D. "object" and "number"
Explanation: typeof null returning "object" is a long-standing bug in the language. NaN is a numeric value. ALSO KNOW (related points): • Which description of JavaScript's typing is correct? → Dynamically and weakly typed • What is the maximum number of nodes in a binary tree of height h (where a tree with only a root has height 0)? → 2^(h+1) - 1

Correct Answer: B. Stack: LIFO; Queue: FIFO
Explanation: A stack adds and removes at one end. A queue adds at the rear and removes from the front.

Correct Answer: B. Average O(1); worst O(n)
Explanation: When many keys collide in one bucket, lookup degrades to linear time. ALSO KNOW (related points): • Which pairing of abstract data type and access order is correct? → Stack: LIFO; Queue: FIFO • Which statement best defines an Abstract Data Type (ADT)? → A type defined by its operations and behavior, independent of how it is implemented

Correct Answer: B. 2^(h+1) - 1
Explanation: Each level L holds at most 2^L nodes. Summing levels 0 to h gives 2^(h+1) - 1.

Correct Answer: D. A type defined by its operations and behavior, independent of how it is implemented
Explanation: For example, a Stack ADT can be implemented with an array or with a linked list.