[프로그래머스] 전화번호 목록

 

import java.util.*;

class Solution {
    public boolean solution(String[] phone_book) {
        
        Map<String, String> hm = new HashMap<String, String>();
        
        for(int i=0; i<phone_book.length-1; i++){
            for(int j=i+1; j<phone_book.length; j++){
                if(phone_book[i].startsWith(phone_book[j])) return false;
                if(phone_book[j].startsWith(phone_book[i])) return false;
            }
        }
        return true;
    }
}