This problem is a very tricky one. Basically the result is made of a product of some elements divided by the product of other elements. In the given example, we can see `1000/(100/10/2) == (1000*10*2)/(100)`

.

And one thing we shall notice is **"NOTE 2. Elements in the given array will be in range [2, 1000]."** What does it mean? It means every element can contribute to a bigger results as long as it's **NOT** in the denominator part! And we know no matter how we add parenthesis, the second element must be in the denominator if it exist. And that's it!

```
class Solution(object):
def optimalDivision(self, nums):
"""
:type nums: List[int]
:rtype: str
"""
nums = list(map(str, nums))
if len(nums) > 2:
nums[1] = "(" + nums[1]
nums[-1] = nums[-1] + ")"
return "/".join(nums)
```