题目链接:
subsets-ii[java]
view plain copyimport java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
*
Given a collection of integers that might contain duplicates, S, 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 S = [1,2,2], a solution is:
[
[2],
[1],
[1,2,2],
[2,2],
[1,2],
[]
]
*
*/
public class SubsetsII {
// 19 / 19 test cases passed.
// Status: Accepted
// Runtime: 259 ms
// Submitted: 0 minutes ago
//时间复杂度O(2^n) 空间复杂度 O(n)
//偷懒了,直接用了set容器,去除重复子集
public Set<List<Integer>> subsets = new HashSet<List<Integer>>();
public List<List<Integer>> subsetsWithDup(int[] num) {
Arrays.sort(num);
subsets(num, 0, new ArrayList<Integer>());
return new ArrayList<List<Integer>>(subsets);
}
public void subsets(int[] S, int step, List<Integer> subset) {
if(step == S.length) {
subsets.add(subset);
return;
}
//num[step] 不加入子集中
subsets(S, step + 1, new ArrayList<Integer>(subset));
//num[step] 加入子集中
subset.add(S[step]);
subsets(S, step + 1, new ArrayList<Integer>(subset));
}
public static void main(String[] args) {
// TODO Auto-generated method stub
}
}
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