Subsets II(待研究)---位运算法(重要和Combination Sum一系列的题目类似)
第一题、78.SubsetsGivenasetofdistinctintegers,nums,returnallpossiblesubsets.Note:Thesolutionsetmustnotcontainduplicatesubsets.Forexample,Ifnums=[1,2,3],asolutionis:[[3],[1],[2],[1,2,3],[1,3],[2,3],[1,2],[