独特的电子邮件地址（力扣题库）

   public static void main(String[] args) {
        String[] emails = new String[]{"[email protected]","[email protected]","[email protected]"};

        System.out.println(numUniqueEmails(emails));

    }
    public static int numUniqueEmails(String[] emails){
        Map<String,String> map = new HashMap<>();
        for (int i = 0; i < emails.length; i++) {
            StringBuilder builder = new StringBuilder(emails[i]);
            String qian = builder.substring(0, builder.indexOf("@"));
            builder = new StringBuilder(emails[i]);
            String hou = builder.substring(builder.indexOf("@"), builder.length());
            if (qian.indexOf(".")!=-1){
                qian=qian.replace(".","");
            }
            if (qian.indexOf("+")!=-1){
                qian=qian.substring(0,qian.indexOf("+"));
            }
            String email = qian+hou;
            if (map.get(email)==null){
             map.put(email,email);
         }
        }
        return map.size();
    }