자동차 테스트

https://softeer.ai/practice/info.do?idx=1&eid=1717 

Softeer

 

최초답

import java.util.*;
import java.io.*;


public class Main
{
    public static ArrayList<Integer> carList = new ArrayList<Integer>();
    
    public static final int notFound = -1;

    public static void main(String args[]) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(in.readLine());
        int carCnt = Integer.parseInt(st.nextToken());
        int qCnt = Integer.parseInt(st.nextToken());
        
        st = new StringTokenizer(in.readLine());
        for (int i = 0; i < carCnt; i++){
            carList.add(Integer.parseInt(st.nextToken()));
        }
        Collections.sort(carList);

        for (int i = 0; i < qCnt; i++){
            int value = Integer.parseInt(in.readLine());
            System.out.println(getKindsOfTest(value));
        }
    }

    public static int getKindsOfTest(int value){
        int index = getIndex(value);
        if (index == notFound){
            return 0;
        }
        int overCnt = carList.size() - index - 1;
        int lowerCnt = carList.size() - 1 - overCnt;
        if (overCnt < 0 || lowerCnt < 0){
            return 0;
        }
        return overCnt * lowerCnt;
    }

    public static int getIndex(int value){
        for (int i =0; i < carList.size(); i++){
            if (carList.get(i) == value){
                return i;
            }
        }
        return notFound;
    }
}

수정답

import java.util.*;
import java.io.*;


public class Main
{
    public static int[] carList;
    
    public static final int notFound = -1;

    public static int carCnt;

    public static void main(String args[]) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(in.readLine());
        carCnt = Integer.parseInt(st.nextToken());
        carList = new int[carCnt];
        int qCnt = Integer.parseInt(st.nextToken());
        
        st = new StringTokenizer(in.readLine());
        for (int i = 0; i < carCnt; i++){
            carList[i] = Integer.parseInt(st.nextToken());
        }
        Arrays.sort(carList);

        for (int i = 0; i < qCnt; i++){
            int value = Integer.parseInt(in.readLine());
            System.out.println(getKindsOfTest(value));
        }
    }

    public static int getKindsOfTest(int value){
        int index = getIndex(value);
        if (index < 0){
            return 0;
        }
        int overCnt = carCnt - index - 1;
        int lowerCnt = carCnt - 1 - overCnt;
        if (overCnt < 0 || lowerCnt < 0){
            return 0;
        }
        return overCnt * lowerCnt;
    }

    public static int getIndex(int value){
        return Arrays.binarySearch(carList, value);
    }
}

배운점

값을 검색하여 인댁스를 가져오는 행위에 대하여 ArrayList 를 사용하기보단 array를 사용하는게 선응적으로 이점이있다.

 

코테에서는 가급적 인덱스를 사용하여 값을구하는 행위가 있을 경우 ArrayList는 피해야겠다.

 

익숙해져서 쓰고있었는데.. 아쉽... 시간초과 방지를 하자..