Given a set of distinct integers, nums, return all possible subsets.
Note:
- Elements in a subset must be in non-descending order.
- The solution set must not contain duplicate subsets.
For example,
If nums = 1,2,3, a solution is:
[
3,
1,
2,
1,2,3,
1,3,
2,3,
1,2,
[]
]
代码语言：txt复制 int target;// 次数
Integer[] stack;// 存储每次排列
List<List<Integer>> rt;// 存储结果
public void search(int p, int[] nums) {
// 若长度为k，则stack是其中一个结果，保存结果
if (p == target) {
rt.add(new ArrayList<Integer>(Arrays.asList(stack)));
return;
}
for (int i = 0; i < nums.length; i ) {
if (p > 0 && nums[i] <= stack[p - 1]) {
continue;
}
stack[p] = nums[i];
search(p 1, nums);
}
}
public List<List<Integer>> subsets(int[] nums) {
Arrays.sort(nums);
rt = new ArrayList<List<Integer>>();
// 分别做0~num.length长度的组合
for (int i = 0; i <= nums.length; i ) {
target = i;
stack = new Integer[i];
search(0, nums);
}
return rt;
}
