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HMMT 二月 2001 · 冲刺赛 · 第 29 题

HMMT February 2001 — Guts Round — Problem 29

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [10] Count the number of sequences a , a , a , a , a of integers such that a ≤ 1 for 1 2 3 4 5 i all i and all partial sums ( a , a + a , etc.) are non-negative. 1 1 2 2
解析
  1. [10] Count the number of sequences a , a , a , a , a of integers such that a ≤ 1 for 1 2 3 4 5 i all i and all partial sums ( a , a + a , etc.) are non-negative. 1 1 2 Solution: C (length + 1) = C (6) = 132 . 2