78. 子集

  1. class Solution {
  2.     public List<List<Integer>> subsets(int[] nums) {
  3.         List<List<Integer>> ans = new ArrayList<>();
  4.         if (nums == null || nums.length == 0)
  5.             return ans;
  7.         List<Integer> currSubSet = new ArrayList<>();
  8.         dfs(nums, 0, currSubSet, ans);
  10.         return ans;
  11.     }
  13.     private void dfs(int[] nums, int index, List<Integer> currSubSet, List<List<Integer>> ans) {
  14.         ans.add(new ArrayList<>(currSubSet));
  16.         for (int i = index; i < nums.length; i++) {
  17.             currSubSet.add(nums[i]);
  18.             dfs(nums, i + 1, currSubSet, ans);
  19.             currSubSet.remove(currSubSet.size() - 1);
  20.         }
  21.         return;
  22.     }
  23. }