Python自动出小学生口算题

为了给孩子出计算题，老父亲花了十分钟写了个Python自动出题，20以内加减法以及考察99表的乘除法。
打印结果后粘贴到Word，调整一下格式。

if __name__ == '__main__':
    import random

    for i in range(0,10):
        s = ""
        for i in range(0, 3):

            type = random.randint(1, 4)
            if type == 1:
                a = random.randint(1, 20)
                b = random.randint(1, 20)
                s += "%3d + %3d =          " % (a, b)
            elif type == 2:
                a = random.randint(1, 20)
                b = random.randint(1, 20)
                if a < b:
                    tmp = a
                    a = b
                    b = tmp
                s += "%3d - %3d =          " % (a, b)
            elif type == 3:
                a = random.randint(2, 9)
                b = random.randint(2, 9)
                s += "%3d x %3d =          " % (a, b)
            elif type == 4:
                a = random.randint(2, 9)
                b = random.randint(2, 9)
                s += "%3d / %3d =          " % (a * b, b)
            else:
                print ('type is %d' % type)
        print (s)

再写一个版本，出题加回答。

import random
import sys


def get_r_opr():
    i = random.randint(0, 3)
    if i == 0:
        return "+"
    elif i == 1:
        return "-"
    elif i == 2:
        return "*"
    else:
        return "/"

if __name__ == '__main__':
    while True:
        x = random.randint(0, 100)
        y = random.randint(0, 100)
        z = random.randint(0, 100)
        op1 = get_r_opr()
        op2 = get_r_opr()

        type = random.randint(0, 1)
        if type == 0:
            expression = "%s %s %s %s %s" % (x, op1, y, op2, z)
        else:
            expression = "%s %s %s" % (x, op1, y)
        ret = eval(expression)
        if ret < 0 or int(ret) != ret or ("*" in expression and ret > 100):
            continue
        print("%s = ? " % expression)
        correct = False
        while not correct:
            answer = input("请输入答案(输入q后回车可退出程序, 输入s后回车可跳过此题):")
            if answer.lower() == "s":
                correct = True
                continue
            if answer.lower() == "q":
                sys.exit()
            try:
                answer = int(answer)
            except Exception as ex:
                print("必须输入整数答案")
                continue
            if answer != int(ret):
               print("不对")
               continue
            else:
               print("恭喜，正确。")
               correct = True