// 计时

#pragma once

#include <iostream>

#include <thread>

#include <chrono>

#include <ctime> // clock

namespace DS

{

    // 当n超过一定次数时，栈溢出，比如10万次时：0x005753E9 处有未经处理的异常(在 DS.exe 中): 0xC00000FD: Stack overflow

    // 实际项目中慎用递归，实际项目中一般会设置最大递归次数，若到达最大递归次数哪怕没求得结果也要返回，防止程序栈破裂，程序终止

    void PrintN_Recursive(int n)

    {

        // 递归终止条件

        if (n <= 1) {

            return;

        }

        //std::cout << n << ' ';// 放在这就会逆序打印

        PrintN_Recursive(--n);

        std::cout << n << std::endl;

    }

    void PrintN_Loop(int n)

    {

        for (int i = 1; i <= n; ++i) {

            std::cout << i << std::endl;

        }

    }

    void PrintN_Test()

    {

        clock_t start_time = 0, end_time = 0;

        int n = 0;

        std::cout << "Input N:";

        std::cin >> n;

        std::cout << "By loop:" << std::endl;

        start_time = clock();// C语言方式计时

        DS::PrintN_Loop(n);

        end_time = clock();

        std::cout << "duration:" << end_time - start_time << "ms" << std::endl;

        //std::cout << "duration:" << (end_time - start_time) / CLOCKS_PER_SEC << "s" << std::endl; // CLK_TCK或CLOCKS_PER_SEC是每秒走过的时钟打点数

        std::this_thread::sleep_for(std::chrono::milliseconds(3000));

        std::cout << "By Recursive:" << std::endl;

        auto start = std::chrono::steady_clock::now(); // C++11

        DS::PrintN_Recursive(n);// 当n超过一定次数时，栈溢出，比如1万次时：0x005753E9 处有未经处理的异常(在 DS.exe 中): 0xC00000FD: Stack overflow

        auto end = std::chrono::steady_clock::now();

        auto dura = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();// 微妙

        std::cout << "duration:" << dura * 0.001  << "ms" << std::endl;

    }

}