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],
  []
]

 

这道题也是需要注意不能重复。所以backtracking里需要加sentinel

 

 

public IList<IList<int>> Subsets(int[] nums) {
        var res = new List<IList<int>>();
        Backtracking(nums,new List<int>(),res,0);
        return res;
    }
    
    private void Backtracking(int[] nums,  IList<int> cur,IList<IList<int>> res,int sentinel)
    {
      
            res.Add(new List<int>(cur));
       
        for(int i =sentinel ;i< nums.Count();i++)
        {
            cur.Add(nums[i]);
            Backtracking(nums,cur,res,i+1);
            cur.RemoveAt(cur.Count()-1);
        }
    }