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HMMT 二月 2002 · 冲刺赛 · 第 23 题

HMMT February 2002 — Guts Round — Problem 23

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [5] Find P (7 , 3).
解析
  1. Find P (7 , 3). ( ) n + m Solution: The number of paths that start at (0 , 0) and end at ( n, m ) is , since we n must choose n of our n + m steps to be rightward steps. In this case, the answer is 120 .