使用stream流 ,比其他方法复杂点,但是比较清晰。时间复杂度和空间复杂度都不是太好
import java.util.*;
import java.util.stream.Collectors;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
char[] cList = scan.nextLine().toCharArray();
List<String> list =new ArrayList();
for (int i=0; i < cList.length; i++){
list.add(String.valueOf(cList[i]));
}
Collections.reverse(list);
list = list.stream().distinct().collect(Collectors.toList());
for(String a:list){
System.out.print(a);
}
}
}