针对“自动出题分类计算展示结果系统”的分析，改进建议与阅读心得

#include<iostream>
#include<time.h>
#include<string>
using namespace std;

int main()
{
    int num;
    int div;
    int x, y, m, i, j, t,s;
    cout << "请输入要定制的题数：" ;
    cin >> num;
    cout << "除数显示：1.显示整数；2.显示余数；3.显示分数"<<endl<<"请选择：";
    cin >> div;
    string *res1 = new string[num];
    string *res2 = new string[num];
    string *res3 = new string[num];
    string *a = new string[num];
    string *b = new string[num];
    srand(time(0));
    for (i = 0; i<num;)
    {
        x = rand() % 100;   //0~99
        y = rand() % 100;
        m = rand() % 4;
        b[i] = to_string(x) + to_string(m) + to_string(y);
        for (j = 0; j < i; j++)
            if (a[j] == b[i])
                break;
        if (j == i) {
            switch (m)
            {
            case 0:
                s = x + y;
                if (s > 0 && s < 100) {
                    cout << x << "+" << y << "=" << "\t";
                    res1[i] = to_string(s);
                    res2[i] = to_string(s);
                    res3[i] = to_string(s);
                    i++;
                }
                break;
            case 1:
                if (x < y)
                {
                    t = x;
                    x = y;
                    y = t;
                }
                cout << x << "-" << y << "=" << "\t";
                res1[i] = to_string(x - y);
                res2[i] = to_string(x - y);
                res3[i] = to_string(x - y);
                i++;
                break;
            case 2:
                s = x * y;
                if (s > 0 && s < 100) {
                    cout << x << "*" << y << "=" << "\t";
                    res1[i] = to_string(s);
                    res2[i] = to_string(s);
                    res3[i] = to_string(s);
                    i++;
                }
                break;
            case 3:
                if (y != 0) {
                    cout << x << "/" << y << "=" << "\t";
                    res1[i] = to_string(x / y);
                    res2[i] = to_string(x / y) + "..." + to_string(x % y);
                    res3[i] = to_string(x) + '/' + to_string(y);
                    i++;
                }
            }
        }

    }
    cout << endl;
    cout << "题目答案为：" << endl;
    switch (div)
    {
    case 1:
        for (i = 0; i < num; i++)
            cout << res1[i] << "\t";
        break;
    case 2:
        for (i = 0; i < num; i++)
            cout << res2[i] << "\t";
        break;
    case 3:
        for (i = 0; i < num; i++)
            cout << res3[i] << "\t";
    default:
        break;
    }
    cout << endl;
    return 0;
}