第78題，題目如下:
Given an integer array nums of unique elements, return all possible
(the power set).
The solution set must not contain duplicate subsets. Return the solution in any order.
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]]
Constraints:
1 <= nums.length <= 10-10 <= nums[i] <= 10- All the numbers of
numsare unique.
搜尋，搜到尾的那種，先從沒有的，再到加一個進去，然後再到多個。
最後是從頭加上去，然後從尾開始去除，減到剩下空值。
// Q78. Subsets
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> ans = new ArrayList<>();
dfs(nums, 0, new ArrayList<>(), ans);
return ans;
}
private void dfs(int[] nums, int s, List<Integer> path, List<List<Integer>> ans) {
ans.add(new ArrayList<>(path));
for (int i = s; i < nums.length; ++i) {
path.add(nums[i]);
dfs(nums, i + 1, path, ans);
path.remove(path.size() – 1);
}
}
