LeetCode 205 solution

problem

Given two strings s and t, determine if they are isomorphic.

Two strings s and t are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character, but a character may map to itself. 

Example 1:

• Input: s = "egg", t = "add"
• Output: true

Example 2:

• Input: s = "foo", t = "bar"
• Output: false

python

from typing import List


class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        res = False
        if self.freq_dict(s) == self.freq_dict(t):
            res = True
        return res

    def freq_dict(self, s: str) -> List:
        res = []
        appear = []
        for i in s:
            if i not in appear:
                appear.append(i)
                res.append(appear.index(i))
            else:
                res.append(appear.index(i))
        return res

hash table을 사용하는 것이 좋을 것이다. 이 방식대로 풀면 `O(n^2)` 에 가까워지기 때문에 사실상 시간 복잡도나 공간 복잡도 측면에서 좋은 풀이법은 아니다.