题目描述

n<=39   f(n)=   0,  n=0
                   =    1, n=1
                   = f(n-1)+f(n-2)

public class Solution {
    public int Fibonacci(int n) {
        if(n==0) return 0;
        if(n==1) return 1;
        int one=1;
        int two=0;
        int sum=0;
        for(int i=2;i<=n;i++){
            sum=one+two;
            two=one;
            one=sum;
        }
        return sum;
    }
}