HMMT 二月 2000 · 团队赛 · 第 4 题
HMMT February 2000 — Team Round — Problem 4
题目详情
英文原题
- All arrangemen ts of letters VNNWHT AAIE are listed in lexi ographi (di tionary) order. If AAEHINNTVW is the rst en try , what en try number is V ANNA WHITE? 1
解析
英文解析
- 738,826 . This an be arriv ed at b y stepping do wn, starting with nding ho w man yom binations are there that b egin with a letter other than V or W, and so forth. The
8 9! 4 7!
answ er is + + 4 6! + 4 4! + 3! + 2! + 2! = 738826 .
2 2 2