Fibonacci number

Learning goals ：

A daily topic - Fibonacci number

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Learning content ：

Fibonacci number （ Usually use F(n) Express ） The sequence formed is called Fibonacci sequence . The sequence is composed of 0 and 1 Start , Each of the following numbers is the sum of the first two numbers . That is to say ：

solution ：

class Solution:
    def fib(self, n: int) -> int:
        if n == 0:
           return 0
        if n == 1:
            return 1
        return self.fib(n-1)+self.fib(n-2)