摘要： Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. Example 1: Exampl 阅读全文

摘要： 1. Reverse Nodes in k-Group Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. k is a positive integer 阅读全文

摘要： Given an input string (s) and a pattern (p), implement regular expression matching with support for '.' and '*'. The matching should cover the entire  阅读全文

摘要： 1. 合唱团 有 n 个学生站成一排，每个学生有一个能力值，牛牛想从这 n 个学生中按照顺序选取 k 名学生，要求相邻两个学生的位置编号的差不超过 d，使得这 k 个学生的能力值的乘积最大，你能返回最大的乘积吗？ 思路：想到了用dp来解这题，但是接下来建立dp模型时却遇到了很多困难，尝试用 dp[n 阅读全文

摘要： There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity sh 阅读全文

摘要： We have a list of bus routes. Each routes[i] is a bus route that the i-th bus repeats forever. For example if routes[0] = [1, 5, 7], this means that t 阅读全文

摘要： 1. Number of Islands 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 阅读全文

摘要： 1. Linked List Cycle II Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked 阅读全文

摘要： 1. Sum Root to Leaf Numbers Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the ro 阅读全文

摘要： 1. Convert Sorted List to Binary Search Tree Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced 阅读全文