# Python基础知识点考试系统
# 功能：题库查看、随机抽题考试、成绩统计与错题分析
# 覆盖知识点：函数、循环、条件判断、列表/字典、文件操作、异常处理

import random
import time

# 初始化题库（使用列表嵌套字典存储，键：题目、选项、正确答案、知识点）
question_bank = [
    {
        "question": "Python中定义函数的关键字是？",
        "options": ["A. func", "B. def", "C. function", "D. define"],
        "answer": "B",
        "knowledge": "函数定义"
    },
    {
        "question": "以下哪个不是Python的基本数据类型？",
        "options": ["A. int", "B. str", "C. list", "D. array"],
        "answer": "D",
        "knowledge": "数据类型"
    },
    {
        "question": "执行print(10 % 3)的结果是？",
        "options": ["A. 3", "B. 1", "C. 0", "D. 3.33"],
        "answer": "B",
        "knowledge": "算术运算符"
    },
    {
        "question": "Python中循环语句不包含以下哪个？",
        "options": ["A. for", "B. while", "C. do...while", "D. 以上都不是"],
        "answer": "C",
        "knowledge": "循环结构"
    },
    {
        "question": "字典的键值对使用什么符号分隔？",
        "options": ["A. 逗号", "B. 冒号", "C. 等号", "D. 分号"],
        "answer": "B",
        "knowledge": "字典类型"
    },
    {
        "question": "if语句后的条件表达式结尾需要加什么符号？",
        "options": ["A. 分号", "B. 冒号", "C. 逗号", "D. 不需要"],
        "answer": "B",
        "knowledge": "条件判断"
    },
    {
        "question": "列表的索引从几开始？",
        "options": ["A. 0", "B. 1", "C. -1", "D. 任意"],
        "answer": "A",
        "knowledge": "列表操作"
    },
    {
        "question": "打开文件的函数是？",
        "options": ["A. open()", "B. read()", "C. file()", "D. write()"],
        "answer": "A",
        "knowledge": "文件操作"
    }
]


def show_menu():
    """显示系统主菜单"""
    print("\n===== Python基础知识点考试系统 =====")
    print("1. 查看题库")
    print("2. 开始考试")
    print("3. 退出系统")
    print("====================================")


def view_question_bank():
    """查看完整题库功能"""
    print("\n===== Python基础题库 =====")
    for idx, question in enumerate(question_bank, 1):
        print(f"\n{idx}. {question['question']}")
        print("   选项：", " | ".join(question['options']))
        print(f"   正确答案：{question['answer']}")
        print(f"   知识点：{question['knowledge']}")
    input("\n按回车键返回主菜单...")


def start_exam():
    """开始考试核心功能：随机抽题、限时答题、实时判分"""
    # 1. 设置考试参数
    exam_time = 5  # 每题答题时间（秒），可调整
    question_num = 5  # 抽取题目数量，可调整

    # 2. 随机抽取题目（避免重复）
    if question_num > len(question_bank):
        print(f"题库仅有{len(question_bank)}题，自动调整为全部题目考试")
        question_num = len(question_bank)
    selected_questions = random.sample(question_bank, question_num)

    # 3. 初始化考试数据
    score = 0  # 总分
    wrong_questions = []  # 存储错题
    total_points = question_num * 20  # 总分100分，每题20分

    print(f"\n===== 考试开始 =====\n本次考试共{question_num}题，每题{exam_time}秒答题时间，总分{total_points}分")
    print("请输入选项（A/B/C/D），输入错误将直接判定为答错！")

    # 4. 逐题答题
    for idx, q in enumerate(selected_questions, 1):
        print(f"\n第{idx}题（{exam_time}秒）：{q['question']}")
        print("   选项：", " | ".join(q['options']))

        # 限时答题
        try:
            start_time = time.time()
            user_answer = input("请输入你的答案：").strip().upper()
            used_time = time.time() - start_time

            if used_time > exam_time:
                print(f"答题超时（用时{used_time:.1f}秒），本题不得分！")
                wrong_questions.append({
                    "question": q['question'],
                    "user_answer": "超时未答",
                    "correct_answer": q['answer']
                })
                continue

            # 判分
            if user_answer == q['answer']:
                print("回答正确！")
                score += 20
            else:
                print(f"回答错误！正确答案是：{q['answer']}")
                wrong_questions.append({
                    "question": q['question'],
                    "user_answer": user_answer,
                    "correct_answer": q['answer']
                })
        except:
            print("输入异常，本题判定为答错！")
            wrong_questions.append({
                "question": q['question'],
                "user_answer": "输入异常",
                "correct_answer": q['answer']
            })

    # 5. 成绩统计与展示
    show_score(score, total_points, wrong_questions)

    # 6. 保存成绩到文件
    save_score(score, total_points, wrong_questions)


def show_score(score, total_points, wrong_questions):
    """成绩统计与错题展示功能"""
    print("\n===== 考试结束 ======")
    print(f"你的最终得分：{score}分（总分{total_points}分）")
    accuracy = (score / total_points) * 100 if total_points > 0 else 0
    print(f"答题正确率：{accuracy:.1f}%")

    # 展示错题
    if wrong_questions:
        print(f"\n===== 错题分析（共{len(wrong_questions)}题）=====")
        for idx, wq in enumerate(wrong_questions, 1):
            print(f"\n{idx}. 题目：{wq['question']}")
            print(f"   你的答案：{wq['user_answer']}")
            print(f"   正确答案：{wq['correct_answer']}")
    else:
        print("\n恭喜！你全部答对了！")
    input("\n按回车键返回主菜单...")


def save_score(score, total_points, wrong_questions):
    """将考试成绩保存到文件（文件操作）"""
    try:
        with open("exam_result.txt", "a", encoding="utf-8") as f:
            f.write(f"\n===== 考试成绩记录 =====\n")
            f.write(f"考试时间：{time.strftime('%Y-%m-%d %H:%M:%S')}\n")
            f.write(f"得分：{score}分（总分{total_points}分）\n")
            f.write(f"正确率：{(score / total_points) * 100:.1f}%\n")
            if wrong_questions:
                f.write(f"错题数量：{len(wrong_questions)}题\n")
                for wq in wrong_questions:
                    f.write(f"题目：{wq['question']} | 你的答案：{wq['user_answer']} | 正确答案：{wq['correct_answer']}\n")
        print("成绩已保存到 exam_result.txt 文件！")
    except:
        print("成绩保存失败，请检查文件权限！")


def main():
    """系统主函数：控制整体流程"""
    while True:
        show_menu()
        try:
            choice = int(input("请输入功能编号（1-3）："))
            if choice == 1:
                view_question_bank()
            elif choice == 2:
                start_exam()
            elif choice == 3:
                print("感谢使用Python考试系统，再见！")
                break
            else:
                print("输入错误，请输入1-3之间的数字！")
        except ValueError:
            print("输入格式错误，请输入数字！")


# 程序入口
if __name__ == "__main__":
    main()