[프로그래머스] 전화번호 목록

import java.util.*;

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