1095. Find in Mountain Array
Hard
2K
75

(This problem is an interactive problem.)

You may recall that an array `arr` is a mountain array if and only if:

• `arr.length >= 3`
• There exists some `i` with `0 < i < arr.length - 1` such that:
• `arr < arr < ... < arr[i - 1] < arr[i]`
• `arr[i] > arr[i + 1] > ... > arr[arr.length - 1]`

Given a mountain array `mountainArr`, return the minimum `index` such that `mountainArr.get(index) == target`. If such an `index` does not exist, return `-1`.

You cannot access the mountain array directly. You may only access the array using a `MountainArray` interface:

• `MountainArray.get(k)` returns the element of the array at index `k` (0-indexed).
• `MountainArray.length()` returns the length of the array.

Submissions making more than `100` calls to `MountainArray.get` will be judged Wrong Answer. Also, any solutions that attempt to circumvent the judge will result in disqualification.

Example 1:

```Input: array = [1,2,3,4,5,3,1], target = 3
Output: 2
Explanation: 3 exists in the array, at index=2 and index=5. Return the minimum index, which is 2.```

Example 2:

```Input: array = [0,1,2,4,2,1], target = 3
Output: -1
Explanation: 3 does not exist in `the array,` so we return -1.
```

Constraints:

• `3 <= mountain_arr.length() <= 104`
• `0 <= target <= 109`
• `0 <= mountain_arr.get(index) <= 109`
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