First and Last Positions in a Sorted List

Easy

Question

Given a sorted list, return a list with the start and end positions of a given target value.

If the target isn't in the list, then return [-1, -1].

Note: Solve the problem in O(logn) time.

Input: nums = [0, 2, 4, 5, 5, 5], target = 5

Output: [3, 5]

The first 5 is found at index 3 in the list, and the last 5 is found at index 5 in the list.

Input: nums = [0, 2, 4, 5, 5, 5], target = 2

Output: [1, 1]

The first 2 is found at index 1 in the list, and the last 2 is also at index 1 in the list the list.

Input: nums = [1], target = 3

Output: [-1, -1]

The target 3 is not in this list.

What are some questions you'd ask an interviewer?

What is the first and last positions if given these inputs? nums = [1, 2, 3, 3, 3, 4, 5, 5], target = 2

[-1, -1]

[1, -1]

[-1, 1]

[1, 1]