Find All Elements Equal to K in a Sorted Array Using Only lower_bound

Problem Given a non-decreasing sorted array nums and a target value k, return the index interval [L, R] containing all elements equal to k. If k does not exist, return [-1, -1]. There is an additional restriction: you may only use one binary-search API: lower_bound(x): returns the first index i such that nums[i] >= x; returns n if no such index exists. You are not allowed to implement upper_bound, nor are you allowed to write another variant of binary search. Basic Version Assume all elements in nums are integers. Use only lower_bound to find the interval of all elements equal to k. Follow-up Discussion If the element type is not integer, such as float, string, or a custom comparable object, and the type has no notion of a successor value, is it always possible to find the right boundary in O(log n) using only lower_bound? Explain why or why not. Input Format n k nums[0] nums[1] ... nums[n-1] Output Format L R If the target does not exist, output: -1 -1 Constraints 0 <= n <= 2 * 10^5 nums is sorted in non-decreasing order In the basic version, nums[i] and k are integers Indices are 0-based Example Input: 7 2 1 2 2 2 3 4 5 Output: 1 3 Example Input 7 2 1 2 2 2 3 4 5 Output 1 3