[백준] 10825. 국영수

문제 링크

[백준] 10825. 국영수

풀이 과정

정렬 문제입니다.

다음은 Stream을 이용한 풀이입니다.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = stoi(br.readLine());
        List<Student> list = new ArrayList<>();

        while (N-- > 0) {
            StringTokenizer st = new StringTokenizer(br.readLine());
            list.add(new Student(st.nextToken(), stoi(st.nextToken()), stoi(st.nextToken()), stoi(st.nextToken())));
        }

        list.stream()
                .sorted(Comparator.comparing(Student::getKo).reversed()
                        .thenComparing(Student::getEn)
                        .thenComparing(Comparator.comparing(Student::getMath).reversed())
                        .thenComparing(Student::getName))
                .map(Student::getName)
                .forEach(System.out::println);
    }

    static class Student {
        String name;
        int ko, en, math;

        public Student(String name, int ko, int en, int math) {
            this.name = name;
            this.ko = ko;
            this.en = en;
            this.math = math;
        }

        public int getKo() { return ko; }
        public int getEn() { return en; }
        public int getMath() { return math; }
        public String getName() { return name; }
    }

    public static int stoi(String s) { return Integer.parseInt(s); }
}

@Override
public int compareTo(Student o) {
    if (this.korean == o.korean) {
        if (this.english == o.english) {
            if (this.math == o.math) {
                return name.compareTo(o.name);
            } else {
                return Integer.compare(o.math, this.math);
            }
        } else {
            return Integer.compare(this.english, o.english);
        }
    } else {
        return Integer.compare(o.korean, this.korean);
    }
}

문제의 정렬 규칙에 맞게 위와 같이 compareTo 메서드를 작성할 수 있습니다.

코드

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        ArrayList<Student> list = new ArrayList<>();

        for (int i = 0; i < N; i++) list.add(new Student(sc.next(), sc.nextInt(), sc.nextInt(), sc.nextInt()));

        Collections.sort(list);

        StringBuilder sb = new StringBuilder();

        for (Student student : list) {
            sb.append(student.name);
            sb.append("\n");
        }

        System.out.println(sb);
    }

    static class Student implements Comparable<Student> {
        String name;
        int korean, english, math;

        public Student(String name, int korean, int english, int math) {
            this.name = name;
            this.korean = korean;
            this.english = english;
            this.math = math;
        }

        @Override
        public int compareTo(Student o) {
            if (this.korean == o.korean) {
                if (this.english == o.english) {
                    if (this.math == o.math) {
                        return name.compareTo(o.name);
                    } else {
                        return Integer.compare(o.math, this.math);
                    }
                } else {
                    return Integer.compare(this.english, o.english);
                }
            } else {
                return Integer.compare(o.korean, this.korean);
            }
        }
    }
}