33. Search in Rotated Sorted Array
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

解题思路参考
先判断有序数组，然后binary search

func search(nums []int, target int) int {
	if len(nums) == 0 {
		return -1
	}
	l := 0
	r := len(nums) - 1
	for l+1 < r {
		mid := (l + r) / 2
		if target == nums[mid] {
			return mid
		}
		if nums[l] < nums[mid] {
			if target < nums[mid] && target >= nums[l] {
				r = mid
			} else {
				l = mid
			}
		} else {
			if target > nums[mid] && target <= nums[r] {
				l = mid
			} else {
				r = mid
			}
		}
	}
	if nums[l] == target {
		return l
	}
	if nums[r] == target {
		return r
	}
	return -1
}