题解 | #牛牛学数列5#

C++代码，没用数组的方法

using namespace std;
#define int long long
#define endl '\n'
signed main(){
    std::ios::sync_with_stdio(false); cin.tie(0);cout.tie(0);
   int n;cin>>n;
    int s,f1=1,f2=1;
    if(n<=2)
    {
         cout<<"1"<<endl;
         return 0;
    }      
    for(int i=3;i<=n;i++){    
        s=f1+f2;
        f1=f2,f2=s;
    }
    cout<<s<<endl;
   return 0;
}