DFS_90. 子集 II

输入: [1,2,2]
输出:
[
[2],
[1],
[1,2,2],
[2,2],
[1,2],
[]
]

class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
    Arrays.sort(nums);
    List<List<Integer>> subsets = new ArrayList<>();
    List<Integer> tempSubset = new ArrayList<>();
    boolean[] isVisited = new boolean[nums.length];
    for (int size = 0; size <= nums.length; size++) {
        backtracking(0, tempSubset, subsets, isVisited, size, nums); // 不同的子集大小
    }
    return subsets;
    }

    private void backtracking(int start, List<Integer> tempSubset, List<List<Integer>> subsets, boolean[] isVisited,final int size, final int[] nums) {
        if (tempSubset.size() == size) {
            subsets.add(new ArrayList<>(tempSubset));
            return;
        }
        for (int i = start; i < nums.length; i++) {
            if (i != 0 && nums[i] == nums[i - 1] && !isVisited[i - 1]) {
                continue;
            }
            tempSubset.add(nums[i]);
            isVisited[i] = true;
            backtracking(i + 1, tempSubset, subsets, isVisited, size, nums);
            isVisited[i] = false;
            tempSubset.remove(tempSubset.size() - 1);
        }
    }
}