第1点分类加法计数原理与分步乘法计数原理(★★★★)必做1一个小朋友有5支不同颜色的水彩笔,老师要求用这5支笔给图中的四个区域涂色,规定一个区域只涂一种颜色,相邻的区域颜色不同,那么小朋友有______种不同的涂色方案.牛刀小试精妙解法先分为两类:第一类,当D与A不同色,则可分为四步完成.第一步,涂A有5种方法;第二步,涂D有4种方法;第三步,涂C有3种方法;第四步,涂B有3种方法. The first point classification plus counting principle and the step-by-step multiplication counting principle (1) a child must have 5 different colors of watercolor pen, the teacher asked to use these five pens to paint the four regions in the picture, The provisions of a region only painted a color, the adjacent area of ​​different colors, so children have ______ different kinds of coloring scheme .On the first class, when D and A different color, then Can be divided into four steps to complete the first step, there are five ways to paint A; the second step, there are four ways to paint D; the third step, there are three ways to paint C; the fourth step, there are three ways to paint B .