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Find First and Last Position of Element in Sorted Array
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Find First and Last Index of Element in Sorted List
Problem Statement
Given a sorted list of integers arr in ascending order, determine the first and last positions where a specified key appears.
Your solution should aim for a runtime complexity of approximately O(log n).
If the key is not present in the list, return [-1, -1].
Examples
Input: arr = [2, 4, 4, 6, 6, 9], key = 6
Output: [3, 4]
Input: arr = [2, 4, 4, 6, 6, 9], key = 5
Output: [-1, -1]
Input: arr = [1, 1, 2, 3, 4, 4, 4, 5], key = 4
Output: [4, 6]
Constraints
- 1 ≤ length of
arr≤ 15,000 - -105 ≤ elements of
arr≤ 105 arris sorted in ascending order