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HMMT 二月 2001 · 冲刺赛 · 第 16 题

HMMT February 2001 — Guts Round — Problem 16

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [6] After walking so much that his feet get really tired, the beaver staggers so that, at each step, his coordinates change by either (+1 , +1) or (+1 , − 1). Now he walks from (0 , 0) to (8 , 0) without ever going below the x -axis. How many such paths are there?
解析
  1. [6] After walking so much that his feet get really tired, the beaver staggers so that, at each step, his coordinates change by either (+1 , +1) or (+1 , − 1). Now he walks from (0 , 0) to (8 , 0) without ever going below the x -axis. How many such paths are there? Solution: C (4) = 14 .