#!/usr/bin/env pythonfrom operator import add, sub from random import randint, choiceops = {'+': add, '-':sub}#定義一個字典MAXTRIES = 2 def doprob():  op = choice('+-')  #用choice從'+-'中隨意選擇操作符   nums = [randint(1,10) for i in range(2)]  #用randint(1,10)隨機生成一個1到10的數,隨機兩次使用range(2)   nums.sort(reverse=True)  #按升序排序  ans = ops[op](*nums)  #利用函數  pr = '%d %s %d = ' % (nums[0], op, nums[1])  oops = 0   #oops用來計算failure測試,當三次時自動給出答案  while True:    try:      if int(raw_input(pr)) == ans:        print 'correct'        break      if oops == MAXTRIES:        print 'answer/n %s%d' % (pr, ans)        break      else:        print 'incorrect... try again'        oops += 1    except (KeyboardInterrupt, EOFError, ValueError):      print 'invalid ipnut... try again'def main():  while True:    doprob()    try:      opt = raw_input('Again? [y]').lower()      if opt and opt[0] == 'n':        break    except (KeyboardInterrupt, EOFError):      breakif __name__ == '__main__':  main()

8 - 1 = 7correctAgain? [y]y7 - 1 = 6correctAgain? [y]y9 + 4 = 0incorrect... try again9 + 4 =