Match Substring After Replacement — LeetCode 2301 Python Solution

The problem

You are given two strings s and sub. You are also given a 2D character array mappings where mappings[i] = [oldi, newi] indicates that you may perform the following operation any number of times: Replace a character oldi of sub with newi.

Example

Input

s = "fool3e7bar", sub = "leet", mappings = [["e","3"],["t","7"],["t","8"]]

Output

true

Explanation

Replace the first 'e' in sub with '3' and 't' in sub with '7'.

Python solution

class Solution:
    def matchReplacement(self, s: str, sub: str, mappings: List[List[str]]) -> bool:
        d = defaultdict(set)
        for a, b in mappings:
            d[a].add(b)
        for i in range(len(s) - len(sub) + 1):
            if all(a == b or a in d[b] for a, b in zip(s[i : i + len(sub)], sub)):
                return True
        return False

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2301. Match Substring After Replacement is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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