1、斐波那契数列(两个元素的和确定下一个数)

1 # 1,1,2,3,5,8,13,21,34,55,89...... 2 # 方法一：递归 3 def feb(n): 4     if n == 1 or n == 2: 5         return 1 6     else: 7         return feb(n-1)+feb(n-2) 8 n = 8 9 print(feb(n))10 11 12 # 方法二：循环13 x,y = 0,014 n = 815 for i in range(0,n+1):16     if i == 1 or i == 2:17         x,y = 1,118     else:19         x,y = y,x+y20 print(y)