LeetCode 78. Subsets

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],
  []
]

和上题类似，都是简单dfs，枚举起点，列举不同起点的所有情况。

class Solution {

    void dfs(int b, vector<int> &nums, vector<int> &res, vector<vector<int>> &ans) {

        ans.push_back(res);
        if(b == nums.size())
            return ;
        for(int i=b; i < nums.size(); ++ i)
        {
            res.push_back(nums[i]);
            dfs(i+1, nums, res, ans);
            res.pop_back();
        }
    }
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> ans;
        vector<int> res;
        dfs(0, nums, res, ans);
        return ans;
    }
};