https://www.acmicpc.net/problem/2659 구현 + 정렬 시간복잡도는 널널하다. import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.util.Arrays;import java.util.HashSet;import java.util.Set;class Main { public static void main(String[] args) throws IOException { int[] a = Arrays.stream( new BufferedReader(new InputStreamReader(System.in)) ..