"""
205. Isomorphic Strings
Difficulty: Easy
https://leetcode.com/problems/isomorphic-strings/

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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

Explanation:

The strings s and t can be made identical by:

        • Mapping 'e' to 'a'.

        • Mapping 'g' to 'd'.

Example 2:

Input: s = "f11", t = "b23"

Output: false

Explanation:

The strings s and t can not be made identical as '1' needs to be
mapped to both '2' and '3'.

Example 3:

Input: s = "paper", t = "title"

Output: true



Constraints:

        • 1 <= s.length <= 5 * 10^4

        • t.length == s.length

        • s and t consist of any valid ascii character.
"""


class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        N = len(t)
        seen = {}

        for i in range(N):
            c1, c2 = s[i], t[i]
            if c1 in seen and seen[c1] != c2:
                return False
            elif c1 in seen and seen[c1] == c2:
                continue
            else:
                seen[c1] = c2

        return len(set(s)) == len(set(t))