HMMT 二月 2000 · POW 赛 · 第 11 题
HMMT February 2000 — POW Round — Problem 11
题目详情
英文原题
- Find the number of distributions of a giv en set of m distin t balls in to a giv en set ofn distin t b o xes if each b o x m ust on tain a sp e i number of balls ( m is the numberof balls to be put in to b o x i ). Please state the answ er with only fa torials (not iniom binatorial notation).
2 3
解析
英文解析
- . This is also equal to : : :
m m m
[ m ! m ! m ! ::: m !℄
1 2 3
1 2 3 n
7!