超级楼梯

描述:

有一楼梯共n级，刚开始时你在第一级，若每次只能跨上一级或二级，要走上第n级，共有多少种走法？
现在给你一个正整数n（0<n<40 n="2,则输出1（你只有一种走法，走一步，从第一级到第二级）

Python代码:

水题 竟然是斐波那契数列问题
l = [1,1]
for i in range(2,n):
    l.append((l[i-1] + l[i-2]))
print(l[n-1])

我他妈写了个二叉树运行超时
# 二叉树******************************* start
# from __future__ import print_function
# import math
# import copy
# n=1
#
#
# L = []
#
#
# class TreeNode(object):
# def __init__(self,data,left,right):
# self.data = data
# self.left = left
# self.right = right
#
# def add_tree_node(tn):
# n = tn.data['reminder']
# if n > 0 and tn.right == None:
# #右子孙
# temp = TreeNode({'reminder':n-1,'node_num':1}, None, None)
# tn.right = temp
# add_tree_node(temp)
# if n > 1 and tn.left == None:
# #左子孙
# temp = TreeNode({'reminder':n-2,'node_num':2},None,None)
# tn.left = temp
# add_tree_node(temp)
# elif n == 1 and tn.left == None:
# #左子孙
# temp = TreeNode({'reminder':n-2,'node_num':-1},None,None)
# tn.left = temp
# add_tree_node(temp)
# return
#
#
#
#
# def travel_tree(tn,l):
# l.append(tn.data['node_num'])
# # print(tn.data['node_num'])
# if tn.left == None and tn.right == None and tn.data['node_num'] != -1: #
# L.append(l)
# else:
# if tn.right!=None:
# travel_tree(tn.right, copy.deepcopy(l))
# if tn.left != None:
# travel_tree(tn.left,copy.deepcopy(l))
# l.pop()
# return
#
# def count_method(n):
# if n > 0:
# root = TreeNode({'reminder':n,'node_num':0},None,None)
# add_tree_node(root)
# l = []
# travel_tree(root,copy.deepcopy(l))
# # print(L)
# print(len(L),end='')
# count_method(n)

# 二叉树******************************* end