[Level 2] 전화번호 목록

import java.util.*;

class Solution {
    public boolean solution(String[] phone_book) {
        Arrays.sort(phone_book);
        
        for(int i=0; i<phone_book.length-1; i++) {
            if(phone_book[i+1].startsWith(phone_book[i])) { return false; }
        }
        
        return true;
    }
}