求第n个斐波那契（fibonacci）数

//求第n个fibonacci数#include <iostream>using namespace std;int main(){    int n;    cin>>n;    int fib1=1,fib2=1;    for (int i=3;i<=n;i++)    {        int temp = fib1+fib2;        fib1 = fib2;        fib2 = temp;//交换，保存现有的斐波那契数    }    cout << "第 "<<n<<" 个fibonacci数是："<<fib2<< endl;    return 0;}