n个小球放入m个盒中的问题是排列组合的常见题型,这种题型情形甚多,很多学生混淆不清,本文通过举例说明每一类问题的求解方法.1.球相同,盒子不同1.1盒子不空例1 12个相同的小球放入编号为1,2,3,4的盒子中,问每个盒子中至少有一个小球的不同放法有多少种?解析将12个小球排列成一 The problem of putting n pellets into m boxes is a common type of permutation and combination. There are many cases of this type of problem, and many students are confused. This paper gives an example of how to solve each type of problem.1. , The box is different 1.1 The box is not empty Example 1 12 identical balls into the box numbered 1, 2, 3, 4, ask at least one ball in each box different method of how many? 12 small balls arranged in one