Largest Number After Mutating Substring — LeetCode 1946 Python Solution

The problem

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.

Example

Input

num = "132", change = [9,8,5,0,3,6,4,2,6,8]

Output

"832"

Explanation

Replace the substring "1":

Python solution

class Solution:
    def maximumNumber(self, num: str, change: List[int]) -> str:
        s = list(num)
        changed = False
        for i, c in enumerate(s):
            d = str(change[int(c)])
            if changed and d < c:
                break
            if d > c:
                changed = True
                s[i] = d
        return "".join(s)

Complexity

Pattern: Greedy

Take the locally best option every time — when you can prove that never costs you later. LeetCode 1946. Largest Number After Mutating Substring is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Greedy.

The greedy guide has the Python template for the pattern and the 346 LeetCode problems that use it.

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