原题 The highest building in our city has only one elevator. A request list is made up with N positive numbers. The number

原题 At the beginning of every day, the first person who signs in the computer room will unlock the door, and the last one

原题 Given a sequence of K integers { N1, N2, …, N**K }. A continuous subsequence is defined to be { N**i, N**i+1, …, N**j

算法简介迪杰斯特拉(Dijkstra)是从一个顶点到其余各顶点的最短路径算法，解决的是有权图中最短路径问题。迪杰斯特拉算法主要特点是从起始点开始，采用贪心算法的策略，每次遍历到始点距离最近且未访问过的顶点的邻接节点，直到扩展到终点为止。

原题 A family hierarchy is usually presented by a pedigree tree. Your job is to count those family members who have no chi

原题 Given a non-negative integer N, your task is to compute the sum of all the digits of N, and output every digit of the

原题 This time, you are supposed to find A+B where A and B are two polynomials. Input Specification:Each input file contai

原题 Calculate a+b and output the sum in standard format – that is, the digits must be separated into groups of three by c

为什么需要虚拟环境简单来讲，就是因为不同的项目可能需要不同的python package。但是，往往安装了最新版本的package会覆盖掉原来的，导致原有的项目因为package不同而无法正常工作。最常用的一个办法就是使用 virtuale

本文主要讲使用位运算的一些技巧。 位运算位运算符号 符号 c/cpp python 含义 按位与 a & b a & b 1 & 1 = 1, 1 & 0 = 0, 同1为1, 有0为0 按位或