Question
Given a set of distinct integers, nums, return all possible subsets (the power set).
Note: 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],
[]
]
Follow up
What if the set has duplicate integers?
For example,
If nums = [1,2,2], a solution is:
[
[2],
[1],
[1,2,2],
[2,2],
[1,2],
[]
]
Solution
TODO
Code
class Solution {
public List<List<Integer>> subsetsWithDup(int[] nums) {
Arrays.sort(nums); // only for duplicate
List<Integer> subset = new ArrayList();
List<List<Integer>> results = new ArrayList();
collectSubsets(subset, results, nums, 0);
return results;
}
public void collectSubsets(List<Integer> subset, List<List<Integer>> results, int[] nums, int idx) {
results.add(new ArrayList(subset));
for(int i=idx; i<nums.length; i++) {
if(i>idx && nums[i] == nums[i-1]) continue; // to skip duplicate
subset.add(nums[i]);
collectSubsets(subset, results, nums, i+1);
subset.remove(subset.size()-1);
}
}
}
Performance
TODO