QUESTION:

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

Example 2:

Input: 3
Output: 2
Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.

Example 3:

Input: 4
Output: 3
Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3. 

Note:

0 ≤ N ≤ 30.

EXPLANATION:

斐波那契数列大家都应该清楚了，直接使用递归的方式进行计算就可以。

SOLUTION:

public static int fib(int N) {
        if(N==0) return 0;
        if(N==1) return 1;
        return fib(N-1)+fib(N-2);
}