First & Last Occurences

lets first understand the question We are given a sorted array which may contain duplicate elements we are also given a number x, and we need to find: the first occurrence of x the last occurrence of x we return the indices in the form: [first_index, last_index] if the element is not present, return [-1, -1] sample i/p and o/p Input: arr = [1, 3, 5, 5, 5, 5, 67, 123], x = 5 Output: [2, 5] how to approach the solution I first thought → "can I just loop through the array and find first and last?" yes, but that will take O(n) time since the array is already sorted, we can do better using binary search instead of finding just one occurrence, we modify binary search to find the leftmost occurrence and rightmost occurrence it work by running a binary search twice for first occurrence → move left when found for last occurrence → move right when found step by step arr = [1, 3, 5, 5, 5, 5, 67] find first: mid = 5 → found → move left continue until first position → index 2 find last: mid = 5 → f