205. Isomorphic Strings

Posted 2020-10-01 Premiumlab

https://leetcode.com/problems/isomorphic-strings/description/

 

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.

For example,
Given "egg", "add", return true.

Given "foo", "bar", return false.

Given "paper", "title", return true.

Note:
You may assume both s and t have the same length.

 

 

Sol：

 

 

 

public class Solution {
    public boolean isIsomorphic(String s, String t) {
        // Time O(n) Space O(n)
        
        if (s.length() != t.length()) return false;
        
        final Map<Character, Character> map1 = new HashMap<>();
        final Map<Character, Character> map2 = new HashMap<>();
        
        for (int i = 0; i < s.length(); i++){
            final char c1 = s.charAt(i);
            final char c2 = t.charAt(i);
            
            if (map1.containsKey(c1)){
                if (map1.get(c1) != c2) return false;
            } else {
                map1.put(c1, c2);
            }
            
            if (map2.containsKey(c2)){
                if (map2.get(c2) != c1) return false;
            } else {
                map2.put(c2, c1);
            }
            
            
        }
        
        return true;
        
    }
}