Find Minimum in Rotated Sorted Array in Swift

You are given an array of distinct integers nums that was sorted in ascending order and then possibly rotated at an unknown index k (0 <= k < nums.count): its first k elements were moved, in the same order, to its end. For example, [0,1,2,4,5,6,7] rotated at k = 3 becomes [4,5,6,7,0,1,2], and with k = 0 it stays as it was.

Given nums after the rotation, return its minimum element.

Example 1:

Input: nums = [3,4,5,1,2]
Output: 1
Explanation: The original array was [1,2,3,4,5], rotated at k = 2.

Example 2:

Input: nums = [4,5,6,7,0,1,2]
Output: 0
Explanation: The original array was [0,1,2,4,5,6,7], rotated at k = 3. The middle element, 7, is bigger than the last one, 2, so the values drop somewhere after the middle: that drop is where the minimum is.

Example 3:

Input: nums = [11,13,15,17]
Output: 11
Explanation: The array was not rotated (k = 0), so the minimum is its first element.

Constraints:

• 1 <= nums.count <= 106
• -109 <= nums[i] <= 109
• All the values of nums are distinct.
• nums is sorted in ascending order and possibly rotated.