这道题还没有看到我这种做法emmm就先发一下
这个东西~~(经过玄学操作)~~ 效率奇棒(๑•̀ㅂ•́)و✧
我就分享一下(代码短的一皮)
(提示:本代码只供演示,不能A此题)
(才不是∵没模数)
```cpp
#include<iostream>
using namespace std;
unsigned long long f(register unsigned long long i, register unsigned long long n1, register unsigned long long n2){return i == 1 ? n2 : f(i - 1, n2, n1 + n2);}
unsigned long long fib(register unsigned long long i){return f(i, 1, 1);}
signed main(){
register int n = 0;
cin >> n;
cout << fib(n) << endl;
return 0;
}
```