摘要：
题目描述: Given a set of distinct integers, nums, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution se 阅读全文
摘要：
题目描述: Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n = 4 and k = 2, a solution is: 解题思路: 阅读全文