斐波那契数列

#include
#include

int fibnaci(int index) {
    try {
        if (index >= 0) {
            int arr[3] = { 1, 1, 0 };
            for (int i = 2; i <= index; ++i) {
                arr[2] = arr[0] + arr[1];
                arr[0] = arr[1];
                arr[1] = arr[2];
            }
            return index < 2 ? arr[index] : arr[2];
        }
        else {
            throw std::invalid_argument("index < 0");
        }
    }
    catch (std::exception &e) {
        std::cout << "exception:" << e.what() << std::endl;
        return -1;
    }

}

int main()
{
    for (int i = 0; i < 15; i++) {
        std::cout << fibnaci(i) << "\t";
    }

    std::cout << std::endl;
    system("pause");
    std::cout << fibnaci(-1) << std::endl;
    system("pause");

    return 0;
}