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HMMT 二月 2007 · TEAM2 赛 · 第 3 题

HMMT February 2007 — TEAM2 Round — Problem 3

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [ 20 ] Five people are crowding into a booth against a wall at a noisy restaurant. If at most three can fit on one side, how many seating arrangements accomodate them all?
解析
  1. [ 20 ] Five people are crowding into a booth against a wall at a noisy restaurant. If at most three can fit on one side, how many seating arrangements accomodate them all? Answer: 240 . Three people will sit on one side and two sit on the other, giving a factor of two. Then there are 5! ways to permute the people.