剑指offer---07---动态规划：斐波那契数列

题意

 

分析

简单的动态规划，使用两个临时变量保存。

 

代码

public class Solution {

    public int Fibonacci(int n) {

        if(n<=0)return 0;

        if(n==1||n==2)return 1;

        int index = 3;

        

        int pre=1;

        int last=1;

        int temp = last;

        while(index<=n){

            temp = last;

            last = pre+last;

            pre = temp;

            index++;

        }

        return last;

    }

}