[LeetCode]#509. Fibonacci Number

Environment: Python 3.8

Key technique: Recursive

The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,

F(0) = 0, F(1) = 1
F(n) = F(n - 1) + F(n - 2), for n > 1.

Given n, calculate F(n).

Example 1:

Input: n = 2
Output: 1
Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.

Analysis:

1. If n=0 and n=1, return n.
2. If n>1, use recursive method and return f(n-1)+f(n-2)

Solution:

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

Submissions:

Reference:

https://openhome.cc/Gossip/AlgorithmGossip/FibonacciNumber.htm