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], [] ]
start 的index 是关键
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], [] ]
start 的index 是关键