Leetcode•Apr 23, 2025
Isomorphic Strings
Hazrat Ali
Leetcode
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 * 104t.length == s.lengthsandtconsist of any valid ascii character.
Solution
/**
* @param {string} s
* @param {string} t
* @return {boolean}
*/
const isIsomorphic = (s, t) => {
const map1 = {};
const map2 = {};
for (let i = 0; i < s.length; i++) {
const a = s[i];
const b = t[i];
if ((map1[a] && map1[a] !== b) || (map2[b] && map2[b] !== a)) {
return false;
}
map1[a] = b;
map2[b] = a;
}
return true;
};