Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Your algorithm's runtime complexity must be in the order of O(log n).

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

Solution:

func search(nums []int, target int) int {
    lenN := len(nums)
    
    if lenN == 0 {
        return -1
    }
    if lenN == 1 {
        if nums[0] == target {
            return 0
        }
        if nums[0] != target {
            return -1
        }
    }
    
    start, end := 0, lenN-1
    
    for start+1 < end { //!!
        mid :=  (end+start) /2 
        
        if nums[mid] == target {
            return mid
        }
        if nums[start] < nums[mid]{  // before pivote side
            if nums[start] <= target && target <= nums[mid] {
                end = mid
            }else {
                start = mid
            }
        } else { // after pivote side
            if nums[mid] <= target && target <= nums[end] {
                start = mid
            } else {
                end = mid
            }
        }
    }
    
    if nums[start] == target{
        return start
    }
    if nums[end] == target {
        return end
    }
    return -1
}