Topic39——78. subset

subject ： Give you an array of integers nums , Elements in an array Different from each other . Returns all possible subsets of the array （ Power set ）.
Solution set You can't Contains a subset of repetitions . You can press In any order Returns the solution set .

 Example  1：
 Input ：nums = [1,2,3]
 Output ：[[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]

 Example  2：
 Input ：nums = [0]
 Output ：[[],[0]]

Tips ：
1 <= nums.length <= 10
-10 <= nums[i] <= 10
nums All elements in Different from each other

backtracking ：

class Solution {
    
    public List<List<Integer>> subsets(int[] nums) {
    
        List<List<Integer>> res = new ArrayList<>();
        List<Integer> list = new ArrayList<>();
        res.add(list);
        trySub(nums, 0, res, list);
        return res;
    }

    public void trySub(int[] nums, int index, List<List<Integer>> res, List<Integer> list) {
    
        if(index >= nums.length)
            return;
        for(int i = index; i < nums.length; i++) {
    
            list.add(nums[i]);
            trySub(nums, i + 1, res, list);
            res.add(new ArrayList<>(list));
            list.remove(list.size() - 1);
        }
    }
}