Restore IP Addresses

    public ArrayList<String> restoreIpAddresses(String s) {        // Start typing your Java solution below        // DO NOT write main() function        return restoreIpAddresses(s, 1);    }        public ArrayList<String> restoreIpAddresses(String s, int n) {        ArrayList<String> result = new ArrayList<String>();        if(n == 5) {            if(s.length() == 0) result.add("");            return result;        }else {            for(int i = 1; i < 4 && i <= s.length(); i++) {                String tmp = s.substring(0, i);                if(tmp.charAt(0) == '0' && i > 1) break;                if(Integer.parseInt(tmp) < 256) {                    for(String str : restoreIpAddresses(s.substring(i), n + 1)) {                        if(n == 4) {                            str = tmp + str;                        }else {                            str = tmp + "." + str;                        }                        result.add(str);                    }                }            }        }        return result;    }