[알고리즘문제풀기] 전화번호 목록

문제

내가 작성한 오답

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

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;
    }
}

내가 작성한 정답

// 간신히 통과
채점 결과
정확성: 83.3
효율성: 16.7
합계: 100.0 / 100.0

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;
    }
}

다른 사람들의 정답

import java.util.*;
class Solution {
    public boolean solution(String[] phone_book) {
        Set<String> set = new HashSet<>();
        set.addAll(Arrays.asList(phone_book));

        for (String number : phone_book) {
            String prefix = "";
            for (int i = 0; i < number.length() - 1; i++) {
                prefix += number.charAt(i); 
                if (set.contains(prefix))   
                    return false;
            }
        }
        return true;

    }
}



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

import java.util.Arrays;
import java.util.Collections;
import java.util.Set;
import java.util.stream.Collectors;

class Solution {
    public boolean solution(String[] phone_book) {
        String text = String.format(" %s", String.join(" ", phone_book));
        return !Arrays.stream(phone_book)
            .anyMatch(s -> text.split(String.format(" %s", s)).length > 2);
    }
}