There is an integer array `nums` sorted in ascending order (with **distinct** values). Prior to being passed to your function, `nums` is **possibly rotated** at an unknown pivot index `k`.
Given the array `nums` after the possible rotation and an integer `target`, return the index of `target` if it is in `nums`, or `-1` if it is not.
You must write an algorithm with O(log n) runtime complexity.
**Example 1:**
```
Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4
```
**Example 2:**
```
Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1
```