백준 1931 - Java

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class BJ1931 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int[][] arr = new int[N][2];

        for(int i=0;i<N;i++){
            arr[i][0]=sc.nextInt();
            arr[i][1]=sc.nextInt();
        }
        Arrays.sort(arr, new Comparator<int[]>() {
            @Override
            public int compare(int[] o1, int[] o2) {
                if (o1[1] == o2[1]) {
                    return o1[0] - o2[0];
                }
                return o1[1] - o2[1];
            }
        });
        int count =0;
        int end=0;

        for(int i=0;i<N;i++){
            if(end<=arr[i][0]){
                end=arr[i][1];
                count++;
            }
        }
        System.out.println(count);
    }
}

 

간단한 그리드 문제이다.. (comparator을 곁들인...)