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HMMT 二月 2001 · 冲刺赛 · 第 15 题

HMMT February 2001 — Guts Round — Problem 15

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [6] A beaver walks from (0 , 0) to (4 , 4) in the plane, walking one unit in the positive x direction or one unit in the positive y direction at each step. Moreover, he never goes to a point ( x, y ) with y > x . How many different paths can he walk?
解析
  1. [6] A beaver walks from (0 , 0) to (4 , 4) in the plane, walking one unit in the positive x direction or one unit in the positive y direction at each step. Moreover, he never goes to a point ( x, y ) with y > x . How many different paths can he walk? Solution: C (4) = 14 .