小学生测验系统设计，求解题技巧

Question

小学生测验系统设计
面向小学12年级学生,随机选择两个整数和加减法形成算式要求学生解答。功能要求:
(1)电脑随机出10道题，每题10分，程序结束时显示学生得分;
(2)确保算式没有超出12年级的水平，只允许进行50以内的加减法，不允许两数之
和或之差超出0~50的范围，负数更是不允许的;
(3)每道题学生有三次机会输入答案，当学生输入错误答案时，提醒学生重新输入，如
果三次机会结束则输出正确答案:
(4)对于每道题，学生第一次输入正确答案得10分，第二次输入正确答案得7分，第
三次输入正确答案得5分，否则不得分;(5)总成绩90以上显示“SMART”
(6) 80-90显示“GOOD”，70-80显示“OK”,60-70显示“PASS”，60以下“TRY AGAIN”

Answer 1

#include <iostream>
#include <cstdlib>
#include <ctime>

int main() {
    int score = 0;

    srand(time(0));

    for (int i = 0; i < 10; i++) {
        int num1 = rand() % 51;
        int num2 = rand() % 51;
        char op = (rand() % 2 == 0) ? '+' : '-';
        int result = (op == '+') ? num1 + num2 : num1 - num2;

        std::cout << "Question " << i+1 << ": " << num1 << " " << op << " " << num2 << " = ?" << std::endl;

        for (int j = 0; j < 3; j++) {
            int answer;
            std::cout << "Enter your answer: ";
            std::cin >> answer;
            if (answer == result) {
                if (j == 0)
                    score += 10;
                else if (j == 1)
                    score += 7;
                else
                    score += 5;
                break;
            } else {
                if (j == 2)
                    std::cout << "Wrong answer! The correct answer is " << result << "." << std::endl;
                else
                    std::cout << "Wrong answer! Please try again." << std::endl;
            }
        }
    }

    std::cout << "Your score: " << score << std::endl;

    if (score >= 90)
        std::cout << "SMART" << std::endl;
    else if (score >= 80)
        std::cout << "GOOD" << std::endl;
    else if (score >= 70)
        std::cout << "OK" << std::endl;
    else if (score >= 60)
        std::cout << "PASS" << std::endl;
    else
        std::cout << "TRY AGAIN" << std::endl;

    return 0;
}