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