Isomorphic Strings

205. Isomorphic Strings

Difficulty: Easy

Related Topics: Hash Table, String

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

Example 3:

Input: s = “paper”, t = “title” Output: true

Code:

class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        chardict = {}
        if len(s) != len(t):
            return False
        for i in range(len(s)):
            if s[i] not in chardict:
                if t[i] in chardict.values():
                    return False
                else:
                    chardict[s[i]] = t[i]
            else:
                if chardict[s[i]] != t[i]:
                    return False
        return True

Feedbacks:

I used dictionary to store the values of str1 with each corressponding values of str2. If there’s already exist a key, but if value is different, I return false.