递归

链接

# 计算小明爬楼梯的爬法数量
def clambstairs1(n):
    a = 1
    b = 2
    c = 4
    for i in range(n-3):
        c,b,a = a+b+c,c,b
    return c


def clambstairs2(n):
    fir = {1:1,2:2,3:4}
    if n in fir.keys():
        return fir[n]
    else:
        return clambstairs2(n-1)+clambstairs2(n-2)+clambstairs2(n-3)


if __name__ == "__main__":
    print(clambstairs2(14))
    print(clambstairs1(14))
# 计算小明爬楼梯的爬法数量
def clambstairs