摘要：
vector 判断是否存在某元素: 阅读全文
摘要：
Given a collection of distinct numbers, return all possible permutations. For example, [1,2,3] have the following permutations: 做了几个 backtrack 类的题目了, 阅读全文
摘要：
Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each num 阅读全文
摘要：
Given a set of candidate numbers (C) ( without duplicates ) and a target number (T), find all unique combinations in C where the candidate numbers sum 阅读全文
摘要：
vector 弹出末尾元素 v.pop_back(); 阅读全文