1.知识要点精析1.1基本原理1.1.1分类计数原理:做一件事,完成它可以有n类办法,在第一类办法中有m1种不同的方法,在第二类办法中有m2种不同的方法,……,在第n类办法中有mn种不同的办法,那么完成这件事共有:m1+m2+……+mn种不同的方法。1.1.2.分步计数原理:做一件事,完成它需要分 1. The main points of knowledge analysis 1.1 The basic principles of 1.1.1 Categorical counting principle: to do one thing, to complete it can have n kinds of methods, there are m1 kinds of different methods in the first kind of methods, in the second kind of methods have m2 There are different ways, ..., there are different ways of doing things in category n, so there are a total of: m1 + m2 + ... + mn different ways of doing this. 1.1.2. Step-by-Step Counting Principle: Do one thing and finish it