2.明明的随机数

题目

AC

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		Set<Integer> s = new HashSet<>();
		List<Integer> l = new ArrayList<>();
		
		int n = sc.nextInt();
		sc.nextLine();
		
		int x = 0;
		for(int i=1;i<=n;i++) {
			x = sc.nextInt();
			if(!s.contains(x)) {
				s.add(x);
				l.add(x);
			}
		}
		
		Collections.sort(l);
		System.out.println(l.size());
		
		for(int y:l) {
			System.out.print(y+" ");
		}
		sc.close();
	}
}