Implement binary search lower/upper bounds
Company: Amazon
Role: Machine Learning Engineer
Category: Coding & Algorithms
Difficulty: Medium
Interview Round: Technical Screen
Given a non-decreasing sorted array nums and a target value, implement two functions using binary search:
(
1) lower_bound(nums, target) that returns the smallest index i such that nums[i] >= target (return len(nums) if no such index exists);
(
2) upper_bound(nums, target) that returns the smallest index i such that nums[i] > target (return len(nums) if no such index exists). Achieve O(log n) time and O(
1) extra space, and handle duplicates, empty arrays, and targets outside the array’s value range. Clearly explain your boundary conditions and provide a few test cases to demonstrate correctness.
Quick Answer: This question evaluates a candidate's understanding of binary search algorithms, handling of boundary conditions and duplicates, and the ability to implement efficient index-finding functions on sorted arrays within the Coding & Algorithms domain.
