参考回答：
long long Fib(long long N){long long first = 1;long long second = 1;long long ret = 0;for (int i = 3; i <=N; ++i){ret = first + second;first = second;second = ret;}return second;}
参考回答：
long long Fib(long long N){long long first = 1;long long second = 1;long long ret = 0;for (int i = 3; i <=N; ++i){ret = first + second;first = second;second = ret;}return second;}名师互学网 版权所有 (c)2021-2022 ICP备案号：晋ICP备2021003244-6号
