Rick wants a faster way to get the product of the largest pair in an array. Your task is to create a performant solution to find the product of the largest two integers in a unique array of positive numbers. All inputs will be valid.
Passing [2, 6, 3] should return 18, the product of [6, 3].
```Disclaimer: Mr. Roll will only accept solutions that are faster than his, which has a running time O(nlogn).``` 
```python
max_product([2, 1, 5, 0, 4, 3])              # => 20
max_product([7, 8, 9])                       # => 72
max_product([33, 231, 454, 11, 9, 99, 57])   # => 104874
```
def max_product(a):
    return a.pop(a.index(max(a))) * max(a)
def max_product(a):
    return a.pop(a.index(max(a))) * max(a)