## Description #

Difficulty: **中等**

Related Topics: Array, Binary Search

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`

(`1 <= k < nums.length`

) such that the resulting array is `[nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]]`

(**0-indexed**). For example, `[0,1,2,4,5,6,7]`

might be rotated at pivot index `3`

and become `[4,5,6,7,0,1,2]`

.

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 in* `nums`

.

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
```

**Example 3:**

```
Input: nums = [1], target = 0
Output: -1
```

**Constraints:**

`1 <= nums.length <= 5000`

- -10
^{4}<= nums[i] <= 10^{4} - All values of
`nums`

are**unique**. `nums`

is an ascending array that is possibly rotated.- -10
^{4}<= target <= 10^{4}

## Solution #

Language: **Go**

IOI