[알고리즘] Unique Email Addresses

Problem

Key Point

String 클래스의 subString(), indexOf()

String str = "abcdefg";
str.subString(5);    // fg
str.subString(2,4)   // cd (2포함O, 4포함X)

String email = "abc@naver.com";
str.indexOf("@");	// 3

Code

public class UniqueEmailAddress {
    public int solution(String[] emails) {
        Set<String> emailSet = new HashSet<>();

        for (String email : emails) {
            String localName = getLocalName(email);
            String domainName = getDomainName(email);
            emailSet.add(localName + domainName);
        }
        return emailSet.size();
    }

    private String getDomainName(String email) {
        return email.substring(email.indexOf("@"));
    }

    private String getLocalName(String email) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < email.length(); i++) {
            char c = email.charAt(i);
            if(c == '.') continue;
            if(c == '+') break;
            if(c == '@') break;
            sb.append(c);
        }
        return sb.toString();
    }
    
    public static void main(String[] args) {
        String[] emails = {"test.email+james@coding.com", "test.e.mail+toto.jane@coding.com", "testemail+tom@cod.ing.com"};
        UniqueEmailAddress problem = new UniqueEmailAddress();
        System.out.println(problem.solution(emails));
    }
}