205. Isomorphic Strings

Problem Link

Description

---

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 = "foo", t = "bar"

Output: false

Explanation:

The strings s and t can not be made identical as 'o' needs to be mapped to both 'a' and 'r'.

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.

Solution

---

Python3

class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        
        def construct(s):
            s = list(s)
            mp = {}
            res = ""
            
            for i, x in enumerate(s):
                if x not in mp:
                    mp[x] = len(mp)
                s[i] = mp[x]
                
            return s
        
        return construct(s) == construct(t)