# 747. Largest Number At Least Twice of Others

#### Easy

***

You are given an integer array `nums` where the largest integer is **unique**.

Determine whether the largest element in the array is **at least twice** as much as every other number in the array. If it is, return *the **index** of the largest element, or return* `-1` *otherwise*.

 

**Example 1:**

```
Input: nums = [3,6,1,0]
Output: 1
Explanation: 6 is the largest integer.
For every other number in the array x, 6 is at least twice as big as x.
The index of value 6 is 1, so we return 1.
```

**Example 2:**

```
Input: nums = [1,2,3,4]
Output: -1
Explanation: 4 is less than twice the value of 3, so we return -1.
```

**Example 3:**

```
Input: nums = [1]
Output: 0
Explanation: 1 is trivially at least twice the value as any other number because there are no other numbers.
```

 

**Constraints:**

* `1 <= nums.length <= 50`
* `0 <= nums[i] <= 100`
* The largest element in `nums` is unique.

```python
class Solution:
    def dominantIndex(self, nums: List[int]) -> int:
        highest = -1
        secondhighest = -1
        max_index = -1
        for index, val in enumerate(nums):
            if val >= highest:
                secondhighest = highest
                highest = val
                max_index = index
            elif val > secondhighest:
                secondhighest = val
        if highest < 2*secondhighest:
            return -1
        return max_index
```