Java數(shù)組高效生成所有兩位以上元素的組合：如何用遞歸實(shí)現(xiàn)排列組合？

import java.util.*;  public class CombinationPermutation {      public static void main(String[] args) {         int[] nums = {11, 33, 22};         generateCombinations(nums);     }      public static void generateCombinations(int[] nums) {         for (int i = 2; i <= nums.length; i++) {             combine(nums, i, 0, new ArrayList<>(), new ArrayList<>());         }     }      private static void combine(int[] nums, int k, int start, List<Integer> current, List<List<Integer>> result) {         if (current.size() == k) {             permute(current);             return;         }         for (int i = start; i < nums.length; i++) {             current.add(nums[i]);             combine(nums, k, i + 1, current, result);             current.remove(current.size() - 1);         }     }      private static void permute(List<Integer> current) {         Collections.sort(current);         do {             System.out.println(current);         } while (Collections.nextPermutation(current));     } }