IsomorphicStrings.py

"""
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


Constraints:

1 <= s.length <= 5 * 104
t.length == s.length
s and t consist of any valid ascii character.
"""


class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        if len(s) != len(t):
            return False

        s_to_t = {}
        t_to_s = {}

        for i in range(len(s)):
            char_s, char_t = s[i], t[i]

            if char_s in s_to_t:
                if s_to_t[char_s] != char_t:
                    return False
            else:
                s_to_t[char_s] = char_t

            if char_t in t_to_s:
                if t_to_s[char_t] != char_s:
                    return False
            else:
                t_to_s[char_t] = char_s

        return True


solution = Solution()
print(solution.isIsomorphic("egg", "add"))  # Output: True
print(solution.isIsomorphic("foo", "bar"))  # Output: False
print(solution.isIsomorphic("paper", "title"))  # Output: True