Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given a string num, which represents a large integer. You are also given a 0-indexed integer array change of length 10 that maps each digit 0-9 to another digit. More formally, digit d maps to digit change[d].
You may choose to mutate a single substring of num. To mutate a substring, replace each digit num[i] with the digit it maps to in change (i.e. replace num[i] with change[num[i]]).
Return a string representing the largest possible integer after mutating (or choosing not to) a single substring of num.
A substring is a contiguous sequence of characters within the string.
 
Please complete the following python code precisely:
```python
class Solution:
    def maximumNumber(self, num: str, change: List[int]) -> str:
```