【面试题】剑指offer 9

输入n,输出斐波那契数列的第n个数的值

f(n)=0 n=0

        1 n=1

         f(n-1)+f(n-2) n>1

代码

#include<iostream>#include <stdlib.h>using namespace std;long long Fibonacci(unsigned int n){if(n<=0)return 0;if(n==1)return 1;return Fibonacci(n-1)+Fibonacci(n-2);}long long Fibonacci2(unsigned int n){if (n<2){return n;}long long fibone=1;long long fibtwo=0;long long fibN=0;for (long long int i=2;i<=n;i++){fibN=fibone+fibtwo;fibtwo=fibone;fibone=fibN;}return fibN;}int main(){int ret=Fibonacci(10);int ret2=Fibonacci2(10);cout<<ret<<endl;cout<<ret2<<endl;system("pause");return 0;}