题目:http://www.51nod.com/Challenge/Problem.html#!#problemId=1362 方法一: 设 a 是向下走的步数. b 是向右下走的步数. c 是向下走的步数.如果是走到第 j 列的方案数的话,有: \( a+b = n \) \( b+c = j \) 所以枚举 a 和 j , b 和 c 的值就是确定的,可以用组合数算: \( \sum\limits_{i=0}^{n}\sum\limits_{j=0}^{m}C_{i+j}^{i}*C_{j}…
Archaeologists have discovered a new set of hidden caves in one of the Egyptian pyramids. The decryption of ancient hieroglyphs on the walls nearby showed that the caves structure is as follows. There are n caves in a pyramid, connected by narrow pas…
