与Leetcode78.Subsets的思路完全相同,去重方法:将nums排序,当在某一次循环内遇到相同的数,则跳过。
时间复杂度:
(此界随N增大而渐进)
C++代码:
class Solution {
public:
vector<vector<int>> result;
vector<vector<int>> subsetsWithDup(vector<int>& nums) {
result.push_back({});
sort(nums.begin(), nums.end());
for (int i = 1; i <= nums.size(); i++)
comb(nums.size(), i, {}, nums);
return result;
}
void comb(int n, int k, vector<int> ans, vector<int>& nums)
{
if (k > n)
return;
if (k == 0)
{
result.push_back(ans);
return;
}
if (k == n)
{
for (int i = k; i > 0; i--)
ans.push_back(nums[i - 1]);
result.push_back(ans);
return;
}
for (int i = n; i >= k; i--)
{
if (i < n && nums[i - 1] == nums[i])
continue;
ans.push_back(nums[i - 1]);
comb(i - 1, k - 1, ans, nums);
ans.pop_back();
}
}
};