斐波那契数列的递归与迭代实现方法

• 递归:

# 斐波那契-递归
def fibo_recur(n):
    if n < 1:
        return 0
    elif n < 3:
        return 1
    else:
        return fibo_recur(n-1) + fibo_recur(n-2)
n = int(input('输入一个数字: '))
result = fibo_recur(n)
print('结果是: ',result)

• 迭代:

# 斐波那契-迭代
def fibo_iter(n):
    x,y,z = 1,1,1
    if n < 1:
        return 0
    elif n < 3:
        return 1
    else:
        while n >= 3:
            z = x + y
            x = y
            y = z
            n -= 1
        return z
n = int(input('输入一个数字: '))
result = fibo_iter(n)
print('结果是: ',result)