백준 - 국영수(10825) - 정렬 - Java

1. 문제

https://www.acmicpc.net/problem/10825

2. 풀이

Java에서 클래스로 정렬하는 방법을 보여주는 항목입니다.

Java에서 정렬하는 방법은 2가지가 있는데요,

1. 클래스 안에서 정렬

• class뒤 implements Comparable 해주기.
• Override로 compareTo해주기.

@Override
public int compareTo(Student other) {

▼아래 코드

public static class Student implements Comparable<Student>{
	
	String name;
	int kor;
	int eng;
	int math;
	
	public Student(String n, int k, int e, int m) {
		name = n;
		kor = k;
		eng = e;
		math = m;
	}
	@Override
	public int compareTo(Student other) {
		// TODO Auto-generated method stub
		
		if(this.kor == other.kor && this.eng == other.eng
				&& this.math == other.math)
			return this.name.compareTo(other.name);
		
		if(this.kor == other.kor && this.eng == other.eng)
			return Integer.compare(other.math, this.math);
		
		if(this.kor == other.kor)
			return Integer.compare(this.eng, other.eng);
		
		return Integer.compare(other.kor, this.kor);
		
	}
}

2. Collections.sort 함수 내부에서 정의.

• new Comparator
• Override로 compare해주기

@Override
public int compare(Node o1, Node o2)

Collections.sort(list, new Comparator<Node>() {
	@Override
	public int compare(Node o1, Node o2) {
		if( (o1.kukScore == o2.kukScore) && (o1.EngScore == o2.EngScore) && (o1.MathScore == o2.MathScore)) {
			return o1.name.compareTo(o2.name);
		} else if( (o1.kukScore == o2.kukScore) && (o1.EngScore == o2.EngScore) ) {
			return Integer.compare(o2.MathScore, o1.MathScore);
		} else if( (o1.kukScore == o2.kukScore) ) {
			return Integer.compare(o1.EngScore, o2.EngScore);
		}
		
		return Integer.compare(o2.kukScore, o1.kukScore);
	}
});

✨sort 내부: Comparator - compare(o1, o2),

✨class 내부: Comparable - compareTo(o2)

이렇게 단순하게 생각하기.

---

3. 전체코드

import java.util.*;

public class Main {

	public static void main(String[] args) {
		
		Scanner input = new Scanner(System.in);
		
		int N = input.nextInt();
		
		ArrayList<Student> Stulist = new ArrayList<Student>();
		
		for(int n = 0; n < N; n++) {
			
			String S = input.next();
			int kor = input.nextInt();
			int eng = input.nextInt();
			int math = input.nextInt();
			
			Stulist.add(new Student(S, kor, eng, math));
		}
		
		Collections.sort(Stulist);
		
		for(int i = 0; i < N; i++)
			System.out.println(Stulist.get(i).name);

	}
	
	public static class Student implements Comparable<Student>{
		
		String name;
		int kor;
		int eng;
		int math;
		
		public Student(String n, int k, int e, int m) {
			name = n;
			kor = k;
			eng = e;
			math = m;
		}

		@Override
		public int compareTo(Student other) {
			// TODO Auto-generated method stub
			
			if(this.kor == other.kor && this.eng == other.eng
					&& this.math == other.math)
				return this.name.compareTo(other.name);
			
			if(this.kor == other.kor && this.eng == other.eng)
				return Integer.compare(other.math, this.math);
			
			if(this.kor == other.kor)
				return Integer.compare(this.eng, other.eng);
			
			return Integer.compare(other.kor, this.kor);
			
		}
	}

}