Given a set of distinct integers, S, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. 题目要求 : 求整数数组的所有子集 注意: 1.子集元素按非降序排列 2.不包含重复的子集 解题思路: 求解这类诸如子集的题目,都可以采用回溯…