2021-10-02肥波那期数列

class Solution:
    def fib(self, n: int) -> int:
        if n < 2:
            return n
        
        p, q, r = 0, 0, 1
        for i in range(2, n + 1):
            p, q = q, r
            r = p + q
        
        return r

class Solution:
    def fib(self,n:int) ->int:
        if n<2:
            return n
        p,q,r =0,0,1
        for i in range(2,n+1):
            p,q = q,r
            r = p+q
        return r

class Solution:
    def fib(self,n:int)-> int:
        if n<2:
            return n
        p,q,r =0,0,1
        for i in range(2,n+1):
            p,q = q,r
            r = p+q
        return r

class Solution:
    def fib(self,n:int) ->int:
        if n<2:
            return n

        p,q,r =0,0,1
        for i in range(2,n+1):
            p,q = q,r
            r = p+q
        return r