Fibonacci Number - LeetCode

# 题目

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,

Given N, calculate F(N).

Example 1:

Example 2:

Example 3:

Note:

0 ≤ N ≤ 30.