205. Isomorphic Strings

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

注意 “ab” to "aa" => false 的情况。

class Solution {
    public boolean isIsomorphic(String s, String t) {       
        Character[] map = new Character[256];
        boolean[] visited = new boolean[256];     // "ab" -> "aa" => false
                
        for (int i = 0; i < s.length(); i++) {
            char sChar = s.charAt(i);
            char tChar = t.charAt(i);
            
            if (map[sChar] == null) {
                if (visited[tChar]) {
                    return false;
                }
                map[sChar] = tChar;
            } else if (map[sChar] != tChar) {
                return false;
            }
            
            visited[tChar] = true;
        }
        
        return true;
    }
}