README.md

205. Isomorphic Strings

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.

Solutions (Java)

class Solution {
    public boolean isIsomorphic(String s, String t) {
        Map<Character, Character> hashTwo = new HashMap<>();
        Map<Character, Character> hashOne = new HashMap<>();
        int length = s.length();
        for(int i = 0; i < length; i++){
            char x = s.charAt(i), y = t.charAt(i);
            if(hashOne.containsKey(x) && hashOne.get(x) != y || hashTwo.containsKey(y) && hashTwo.get(y) != x){
            return false;
            }
            hashOne.put(x, y);
            hashTwo.put(y, x);
        }
        return true; 
    }
}