动态的给一个对象添加一些额外的职责, 就增加功能来说, 装饰模式比生成子类更为灵活.

Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).

Given a set of distinct integers, nums, return all possible subsets (the power set).

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.

The set [1,2,3,…,n] contains a total of n! unique permutations.

Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

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.

4SumDesicriptionGiven an array S of n integers, are there elements a, b, c, and d in S such that a

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

3SumDesicriptionGiven an array S of n integers, are there elements a, b, c in S such that a + b +