我一直在遇到这个问题。基本上，我有一个整数列表，例如
I've been having trouble with this problem. Basically, I have a list of integers, such as
list = [1, 2, 3]我想获取每个子集的所有可能排列。我知道在线上也存在类似的问题，但是我找不到一个可以完成所有排列以及每个子集的问题。换句话说，我想要：
I want to get all possible permutations of every subset. I know similar questions exist online, but I couldn't find one that does every permutation as well as every subset. In other words, I want:
function(list) = [], [1], [2], [3], [1, 2], [2, 1], [1, 3], [3,1], [2, 3], [3,2], [1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]我知道即使输入列表很小，输出也会变得非常大。不幸的是，我只是无法弄清楚如何解决这个问题。
I understand the output will get extremely large even for a small input list size. Unfortunately, I just cannot figure out how to do such a problem.
谢谢！
推荐答案我最终使用了这两个功能的组合。不知道它是否按预期工作，但是到目前为止它是否已经正常工作。
I ended up using a combination of these two functions. Not sure if it works as intended, but so far it has been working properly.
// Generates all permutations of a set. Thus, given an input like [1, 2, 3] it changes the null // final_list input to be [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]] static void heappermute(List<List<Integer>> waypoints, int n, List<List<List<Integer>>> final_list) { int i; if (n == 1) { final_list.add(waypoints); } else { for (i = 0; i < n; i++) { heappermute(waypoints, n-1, final_list); if (n % 2 == 1) { swap(waypoints.get(0), waypoints.get(n-1)); } else { swap(waypoints.get(i), waypoints.get(n-1)); } } } } static void swap (List<Integer> x, List<Integer> y) { List<Integer> temp = new ArrayList<>(); temp = x; x = y; y = temp; } // Generates all subsets of a given set. Thus, given a list of waypoints, it will return a list of // waypoint lists, each of which is a subset of the original list of waypoints. // Ex: Input originalSet = {1, 2, 3} // Output: = {}, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3} // Code modified from stackoverflow/questions/4640034/calculating-all-of-the-subsets-of-a-set-of-numbers public static List<List<List<Integer>>> powerSet(List<List<Integer>> originalSet) { List<List<List<Integer>>> sets = new ArrayList<>(); if (originalSet.isEmpty()) { sets.add(new ArrayList<List<Integer>>()); return sets; } List<List<Integer>> list = new ArrayList<List<Integer>>(originalSet); List<Integer> head = list.get(0); List<List<Integer>> rest = new ArrayList<List<Integer>>(list.subList(1, list.size())); for (List<List<Integer>> set : powerSet(rest)) { List<List<Integer>> newSet = new ArrayList<List<Integer>>(); newSet.add(head); newSet.addAll(set); sets.add(newSet); sets.add(set); } return sets; }