算法-斐波那契

def fibbonacci(n):
    if not isinstance(n, int):
        raise ValueError('n is int type')

    resulet = [0, 1]
    if n in resulet:
        return resulet[n]

    fibbo2 = 0  # n-2的项
    fibbo1 = 1  # n-1的项
    fibbon = 0  # n

    for i in range(2, n + 1):
        fibbon = fibbo1 + fibbo2
        fibbo2 = fibbo1  # 记录n-2项
        fibbo1 = fibbon  # 记录n-1项
    return fibbon