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.

Example 1:

    Input: num = "132", change = [9,8,5,0,3,6,4,2,6,8]
    Output: "832"
    Explanation: Replace the substring "1":
    - 1 maps to change[1] = 8.
    Thus, "132" becomes "832".
    "832" is the largest number that can be created, so return it.

Example 2:

    Input: num = "021", change = [9,4,3,5,7,2,1,9,0,6]
    Output: "934"
    Explanation: Replace the substring "021":
    - 0 maps to change[0] = 9.
    - 2 maps to change[2] = 3.
    - 1 maps to change[1] = 4.
    Thus, "021" becomes "934".
    "934" is the largest number that can be created, so return it.

Example 3:

    Input: num = "5", change = [1,4,7,5,3,2,5,6,9,4]
    Output: "5"
    Explanation: "5" is already the largest number that can be created, so return it.

Constraints:

- `1 <= num.length <= 105`
- `num` consists of only digits `0-9`.
- `change.length == 10`
- `0 <= change[d] <= 9`