LeetCode 205. Isomorphic Strings



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

Two strings 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

You may assume both and have the same length.


Python Solution

class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        if len(s) != len(t):
            return False
        mapping = {}
        for c1, c2 in zip(s, t):
            mapping[c1] = c2
        if len(mapping) != len(set(mapping.values())):
            return False

        coverted_s = ""
        for i in range(0, len(s)):
            coverted_s += mapping[s[i]]
        for c1, c2 in zip(coverted_s, t):
            if c1 != c2:
                return False
        return True
  • Time Complexity: ~N
  • Space Complexity: ~N

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