斐波那契数列的python实现

#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param n int整型 
# @return int整型
#
class Solution:
    def Fibonacci(self , n: int) -> int:
        # write code here
        if n<=2:
            return 1
        a = 1
        b = 1
        for i in range(n-2):
            c = a+b
            a, b = b, c
        return c