Hackerrank Algorithms 2

Question 1

What is the time complexity of binary search on a sorted list of n elements?

Accepted Answer

O(log n)

Answer

Binary search halves the search space each iteration, giving O(log n) time complexity.

Question 2

Which Python built-in function returns the index of the leftmost value in a sorted list that is greater than or equal to a target, using the `bisect` module?

Accepted Answer

bisect.bisect_left

Answer

`bisect.bisect_left` returns the leftmost position where the target can be inserted to keep the list sorted.

Question 3

Given a list `nums = [3, 1, 4, 1, 5, 9]`, what does `sorted(nums, reverse=True)` return?

Accepted Answer

[9, 5, 4, 3, 1, 1]

Answer

`sorted()` with `reverse=True` returns a new list sorted in descending order.

Question 4

Which algorithm sorts by repeatedly finding the minimum element from the unsorted portion and placing it at the beginning?

Accepted Answer

Selection Sort

Answer

Selection sort scans the unsorted portion each pass to select the minimum and swap it into position.

Question 5

What is the worst-case time complexity of quicksort?

Accepted Answer

O(n^2)

Answer

Quicksort degrades to O(n²) when the pivot is always the smallest or largest element (already sorted input with bad pivot choice).

(Hackerrank) HackerRank Python Certification Practice Test

(Hackerrank) HackerRank Python Certification Practice Test

Hackerrank Algorithms 2