백준 1946번 : 신입사원 - Java fastio, Arraylist , Collections.sort

https://www.acmicpc.net/problem/1946

1946번: 신입 사원

import java.util.*;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;

class Edge implements Comparable<Edge>{
//    boolean canUse;
    int x, y;
    Edge(int x, int y){
//        canUse = true;
        this.x = x;
        this.y = y;
    }

    @Override
    public String toString() {
        return "(" + x + "," + y + ")";
    }

    @Override
    public int compareTo(Edge edge){
        if(x!=edge.x) return (edge.x - x);
        else return (edge.y - y);
    }
}

public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int t = Integer.parseInt(br.readLine());
        for(int T=0; T<t; T++){
            int n = Integer.parseInt(br.readLine());

            ArrayList<Edge> list = new ArrayList<>();

            for(int i=0; i<n; i++){
                String[] split = br.readLine().split(" ");

                int a= Integer.parseInt(split[0]);
                int b= Integer.parseInt(split[1]);

                list.add(new Edge(a,b));

            }
            Collections.sort(list, Collections.reverseOrder());

            int comp = 10000000;
            int ans = 0;
            for(int i=0; i<n; i++){
                if(comp > list.get(i).y){
                    ans++;
                    comp = list.get(i).y;
                }
            }

            bw.write(Integer.toString(ans));

            bw.write("\n");
        }
        bw.flush();
    }
}