Leetcode/205Isomorphic_Strings.java at main · yayajjiang/Leetcode · GitHub

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import java.util.*; //for hash table

class Solution {
    public boolean isIsomorphic(String s, String t) {

        Hashtable<Integer, Integer> ht = new Hashtable<Integer, Integer>();
        for (int i = 0; i<s.length(); i++){
            //System.out.println(ht.containsKey((int)s.charAt(i)));
            if(ht.containsKey((int)s.charAt(i))){
                //System.out.println(s.charAt(i));
                if(ht.get((int)s.charAt(i)) !=  (int)t.charAt(i)){
                    //System.out.println(ht.get(s.charAt(i)));
                    return false;
                }

            }else{
                if(ht.containsValue( (int)t.charAt(i))){
                    return false; //No two characters may map to the same character
                }
            }

            ht.put((int)s.charAt(i), (int)t.charAt(i));

            //System.out.println(ht);
        }
        return true;
    }
}