HMMT 二月 2000 · POW 赛 · 第 14 题
HMMT February 2000 — POW Round — Problem 14
题目详情
英文原题
- Find the number of w a ys to distribute sev en distin t balls in to three distin t b o xes ifeach b o x m ust on tain a di eren t number of balls, allo wing an empt y b o x.
解析
英文解析
- The b o xes an be in an y order, so we have a factor of 6. Sev en an be partitioned in toh i
7! 7! 7! 7!
three distin t parts as 0,1,6; 0,2,5; 0,3,4; or 1,2,4. So, the answ er is 6 + + + =
0!1!6! 0!2!5! 0!3!4! 1!2!4!
1008 .