题目描述 Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /…

  There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequ…

  You’re given strings J representing the types of stones that are jewels, and S&nbs…

操作系统 进程与线程 What’s the difference between thread and process?A process is an instance of a computer progr…

  Given a list of non-overlapping axis-aligned rectangles rects, write a function pic…

87. Scramble String 题目 Given a string s1, we may represent it as a binary tree by partitioning it to two non-e…

72. Edit Distance 题目 要想把字符串S1变成S2，可以经过若干次下列原子操作： 1.删除一个字符 2.增加一个字符 3.更改一个字符 字符串S1和S2的编辑距离定义为从S1变成S2所需要原子操作的最少次…

  All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: “ACGAA…

  Design and implement a TwoSum class. It should support the following operations:add and find. add ̵…

  Given an input string , reverse the string word by word.  Example: Input: ["t","h","e"," ","s…

  Given a binary tree with n nodes, your task is to check if it’s possible to partition t…

  Given a sorted (in ascending order) integer array nums of n elements and …