[LeetCode] 78. Subsets

[LeetCode] 78. Subsets

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Given a set of distinct integers, nums, return all possible subsets.

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],
  []
]

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給定一個不重複數字的數組，求它的所有子集。
同樣是求長度小於等於|num|的組合，同上題。

---

class Solution {
public:
    void getOneComb(vector<int>& src, int begin, int end, int k, vector<int>& res, vector<vector<int>>& ans) {
        if (k == 0) {
            ans.push_back(res);
            return;
        }
        for (int i=begin; i<end; ++i) {
            res.push_back(src[i]);
            getOneComb(src, i+1, end, k-1, res, ans);
            res.pop_back();
        }
    }

    vector<vector<int>> subsets(vector<int>& nums) {
        int begin = 0;
        int end = nums.size();
        vector<vector<int>> ans;
        vector<int> res;
        int k = end;
        for (int i=0; i<=k; ++i) {
            getOneComb(nums, begin, end, i, res, ans);
        }
        return ans;
    }
};