rambless
火车进站
https://www.nowcoder.com/practice/97ba57c35e9f4749826dc3befaeae109
import java.util.*; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { static List<String> list = new ArrayList<>(); public static void main(String[] args) { Scanner in = new Scanner(System.in); // 注意 hasNext 和 hasNextLine 的区别 while (in.hasNextInt()) { // 注意 while 处理多个 case list.clear(); int n = in.nextInt(); int[] arr = new int[n]; for(int i=0; i<n; i++) { arr[i] = in.nextInt(); } Deque<Integer> stack = new LinkedList<>(); out(arr, stack, 0, 0, ""); Collections.sort(list); for(String s : list) { System.out.println(s); } } } private static void out(int[] arr, Deque<Integer> stack, int i, int n, String str) { if(n==arr.length) { list.add(str); } if(!stack.isEmpty()) { int pop = stack.pop(); out(arr, stack, i, n+1, str+pop+" "); stack.push(pop); } if(i<arr.length) { stack.push(arr[i]); out(arr, stack, i+1, n, str); stack.pop(); } } }