The task is simple: given any positive integer $N$, you are supposed to count the total number of 1’s in the decimal form of the integers from 1 to $N$. For example, given $N$ being 12, there are five 1’s in 1, 10, 11, and 12.

记录刷题时遇到的单词，不断更新中……

preorder traversal 先序遍历
in-order traversal 中序遍历
post-order traversal 后序遍历
level order traversal 层序遍历
quadratic probing 二次方探查法

As an emergency rescue team leader of a city, you are given a special map of your country. The map shows several scattered cities connected by some roads. Amount of rescue teams in each city and the length of each road between any pair of cities are marked on the map. When there is an emergency call to you from some other city, your job is to lead your men to the place as quickly as possible, and at the mean time, call up as many hands on the way as possible.

当自然数$n$依次取$1,2,3,…,N$时，算式$⌊n/2⌋+⌊n/3⌋+⌊n/5⌋$有多少个不同的值？（注：$⌊x⌋$为取整函数，表示不超过$x$的最大自然数，即$x$的整数部分。）

简要介绍

作者是一名学生，需要在手机上记录课表，虽然现在已经有很多的课程表App了，但是有些呢不支持从教务系统导入，有些呢会有很多广告，再有些就是界面很丑啦~

因此，为了能够便捷的查看课表，免去现有的课程表软件带来的烦恼，我决定！开发一款无害的课表软件。于是，这款“课表助手”就应运而生（虽然不是一个App，后面再详细解释），它的作用不是显示课表，而是将教务系统中的课表转为iCalendar文件。iCalendar是一种日历数据交换的标准，既然是标准了，那大家肯定都支持啦，目前已经测试了Win10/Android9/iPadOS13，都可以导入至日历。导入后就可以愉快的使用系统日历查看课表了，不得不说，系统自带的日历界面清新、使用流畅、没有广告（用过的都说好🙄）。

• 脚本安装请查看Greasyfork
• 完整源码请查看Github