摘要：问题 Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: 阅读全文

摘要：问题描述 Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) -- Push element x onto stack. pop() -- 阅读全文

摘要：由于这个问题，涉及了很多知识，例如数据结构里面的哈希表，c++中的迭代器，因此，需要对于每一个疑惑逐一击破。 问题描述 You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', 阅读全文

摘要：问题描述 Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting ad 阅读全文

摘要：问题： Serialize and Deserialize Binary Tree 描述： Serialization is the process of converting a data structure or object into a sequence of bits so that it 阅读全文