剑指offer66题--Java实现，c++实现和python实现 6.斐波那契数列

题目描述
大家都知道斐波那契数列，现在要求输入一个整数n，请你输出斐波那契数列的第n项（从0开始，第0项为0）。
n<=39
java实现

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

c++实现

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

python实现

# -*- coding:utf-8 -*-
class Solution:
    def Fibonacci(self, n):
        if n is 0 or n is 1:
            return n
        a,b = 0,1
        for i in range(n):
            a,b = b,a+b
        return a
        # write code here