# -*- coding:utf-8 -*-#!python3'''下樓問題。從樓上走到樓下共有h個臺階，每一步有兩種走法：走1個臺階，走2個臺階，問有多少可走的方案。用遞歸思想和迭代思想編程''''''分析:問題可以從最后一次是走1步還是兩步,反向考慮'''def take_stairs_recursive(n):  if n == 1:    return 1  elif n == 2:    return 2  else:    return take_stairs_recursive(n-1)+take_stairs_recursive(n-2)'''其實就是斐波那契數列'''def take_stairs(n):  if n == 1:    return 1  if n == 2:    return 2  a,b = 1,2  result = 0  for i in range(3,n+1):    result = a + b    a = b    b = result  return resultprint(take_stairs_recursive(10))print(take_stairs(10))