public boolean isIsomorphic(String s, String t) {
		if (s.length() != t.length())
			return false;
		HashMap<Character, Character> map = new HashMap<Character, Character>();
		HashMap<Character, Character> rmap = new HashMap<Character, Character>();
		for (int i = 0; i < s.length(); i++) {
			char a = s.charAt(i);
			char b = t.charAt(i);

			if (map.containsKey(a) || rmap.containsKey(b)) {
				if (!(map.containsKey(a) & rmap.containsKey(b)))
					return false;
				if (map.get(a) == b && rmap.get(b) == a)
					continue;
				else
					return false;
			} else {
				map.put(a, b);
				rmap.put(b, a);
			}
		}

		return true;
	}