v2.0上线啦！！

先上代码：

#include<cstdio>
#include<ctime>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<iostream>
#include<cmath>
#include<cstring>
#include<windows.h> 
using namespace std;
const int N = 5010;
int n = 0;
int hard;
int x = 0, y = 0;
int res[N];
int a_[N];
int b_[N];
int yxcnb[N];
int test, c_ = -1; 
void print(int x)
{
    system("cls");
    cout << "%" << x;
}
void made_in()
{
    print(10);
    if(hard == 1) 
    {
        n += 10;
        test = 1;
        x += 20, y += 20;
        c_ = 1;
        hard = 3;
        print(100);
        return;
    } 
    if(hard == 2)
    {
        n += 10;
        test = -2;
        x += 20, y += 20;
        hard = 3;
        print(100);
        return;
    }
    print(20);
    if(hard == 3)
    {
        n += 20;
        test = -2;
        x += 20, y += 20;
        hard = 3;
        print(100);
        return;
    }
    if(hard == 4)
    {
        n += 20;
        test = -1;
        x += 25, y += 25;   
        hard = 4;
        print(100);
        return;
    } 
    print(30);
    if(hard == 5)
    {
        n += 30;
        test += -2;
        x += 100, y += 100; 
        hard = 5;
        print(100);
        return;
    }
    if(hard == 6)
    {
        n += 50;
        test = -2;
        x += 100, y += 100;
        hard = 6;
        print(100);
        return;
    }
    print(40);
    if(hard == 7)
    {
        n += 50;
        test = -1;
        x += 100, y += 100;
        hard = 7;
        print(100);
        return;
    }
    if(hard == 8)
    {
        n += 100;
        test = -1;
        x += 100, y += 100;
        hard = 8;
        print(100);
        return;
    }
    print(50);
    if(hard == 9)
    {
        n += 100;
        test = -1;
        x += 500, y += 500;
        hard = 9;
        print(100);
        return;
    }
    if(hard == 10)
    {
        n += 100;
        test = -1;
        x += 500, y += 500;
        hard = 10;//emmmmmm，5秒一道500以内加减乘好像并不是很难 (((
        print(100);
        return;
    }
    print(60);
    if(hard == -1)
    {
        print(70);
        Sleep(1);
        srand(clock());
        int blah = rand() % 10000 + 1;
        int qwq;
        for(int i = 1; i <= 10000; i ++)
        {
            if(i % blah == 0)
            {
                blah += i;
                if(blah >= 10000)
                {
                    qwq = i;
                    break;
                }
            }
        }
        print(80); 
        srand(qwq);
        n = rand() % qwq + 1;//等等，万一很不顺，qwq很大咋办（没事，后面有生成失败
        srand(n); 
        x = rand() % n + 1;
        srand(x);
        y = rand() % x + 1;
        srand(y);
        y = rand() % x + 1;
        //保险起见，多一次保险
        srand(y);
        hard = rand() % 10;//防止变态，不加1了。 
        print(90);
        made_in();//你魔鬼啊：对，我魔鬼 
        print(100);
        return;
    }
    else
    {
        print(100);
        return;
    }
}
int main()
{
    cout << "请输入难度：(越大越难,1-10)，如果想随机挑战，输入-1" << endl;
    cin >> hard; 
    cout << "处理数据中：";
    Sleep(5000); 
    int test, c_ = -1;
    made_in();
    cout << "正在生成中，请稍等。" << endl;
    Sleep(1000);
    system("cls"); 
    if(x > 1000 || y > 1000)
    {
        cout << "生成失败" << endl;
        Sleep(1000);
        cout << "原因：数据范围过大。" << endl;
        Sleep(2000);
        return 0;
    }
    else if(n > 5000)//我觉得是不是应该改一改 
    {
        cout << "生成失败" << endl;
        Sleep(1000);
        cout << "原因：生成时间过长，容易爆栈。" << endl;
        Sleep(2000);
        return 0;
    }
    else if(hard >= n - 1)
    {
        cout << "生成失败" << endl;
        Sleep(1000);
        cout << "原因：难度不科学" << endl;
        Sleep(2000);
        return 0;
    }
    else cout << "生成成功！程序退出后请在桌面中查看。" << endl; 
    if(n > 500)
    {
        n %= 1000;
        if(n > 500)
        {
            n %= 500;
        }
    }    
    if(n > 200) 
    {
        n %= 200;
    }
    //cout << endl;
    //cout << "test:" << n << ' ' << hard << ' ' << x << ' ' << y << ' '; 
    freopen("D:\\吾爱刷题\\口算\\20200812.md", "w", stdout);
    printf("#  今天的口算:\n");
    cout << "# 请在 $ " << int(n / hard) << " $ 分钟内完成。" << endl;
    cout << "## 习题" << endl; 
    for(int i = 0; i < n ;i ++)
    {
        Sleep(1);
        srand(clock());
        int a = rand() % x + 1;
        Sleep(1);
        srand(clock());
        int b = rand() % y + 1;
        Sleep(1);
        int c;
        a_[i] = a, b_[i] = b;
        if(test == -1) 
        {
            srand(clock());
            c = rand() % 3 + 1;
            Sleep(1);
        } 
        else if(test == -2)
        {
            srand(clock());
            c = rand() % 2 + 1;
            Sleep(1);
        }
        else c = c_;
        yxcnb[i] = c; 
        if(c == 1)
        {
            cout << "#### $ " << i + 1 << ": " << a;
            cout << " + " << b;
            res[i] = a + b;
            cout << " =  $" << endl;            
        }
        if(c == 2)
        {
            cout << "#### $ " << i + 1 << ": " << a;
            cout << " - " << b;
            res[i] = a - b;
            cout << " =  $" << endl;
        }
        if(c == 3)
        {
            cout << "#### $ " << i + 1 << ": " << a;
            cout << " × " << b;
            res[i] = a * b;
            cout << " =  $" << endl;
        }
    }
    cout << endl << "****" << endl;
    cout << "## 答案" << endl;
    for(int i = 0; i < n; i ++)
    {
        cout << "#### $ " << i + 1 << ": " << a_[i];
        if(yxcnb[i] == 1) cout << " + ";
        if(yxcnb[i] == 2) cout << " - ";
        if(yxcnb[i] == 3) cout << " × "; 
        cout << b_[i] << " = " << res[i] << " $" << endl;
    } 
    cout << endl;
    fclose(stdout);
    return 0;   
} 

收藏不亏！

这次为各位魔鬼玩家带来了魔鬼模式，按下-！-1!
然后还增加了自动调整难度功能！
以及答案功能~
考虑到各位的打印机，把3级标题改成了4级标题。
然后缩小了范围。
重要的事情说10遍：

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹

请自行建好文件夹