Problem
Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.
Your algorithm’s runtime complexity must be in the order of O(log n).
If the target is not found in the array, return [-1, -1].
Example 1:
Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]Example 2:
Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]Solution
Do binary search twice for finding left and right boundaries.
Complexity
Although there are two binary search manipulations, it’s time complexity is still O(2logn) = O(logn) if n denotes to length of nums.
It’s trivial that space complexity is O(1).
