枚举
枚举
计算24点
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import itertools ''' 测试 cards = [1, 1, 3, 6] 四个元素的计算结果为24 ''' def twentyfour(cards): '''史上最短计算24点代码''' for nums in itertools.permutations(cards): # 四个数(迭代获取所有随机组合)4!个 for ops in itertools.product('+-*/', repeat=3): # 三个运算符(可重复!)4**3个 # 构造三种中缀表达式 (bsd) bds1 = '({0}{4}{1}){5}({2}{6}{3})'.format(*nums, *ops) # (a+b)*(c-d) bds2 = '(({0}{4}{1}){5}{2}){6}{3}'.format(*nums, *ops) # (a+b)*c-d bds3 = '{0}{4}({1}{5}({2}{6}{3}))'.format(*nums, *ops) # a/(b-(c/d)) for bds in [bds1, bds2, bds3]: # 遍历 try: if abs(eval(bds) - 24.0) < 1e-10: # eval函数 return bds except ZeroDivisionError: # # 零除错误! continue return 'Not found!' # 测试 cards = [1, 1, 3, 6] print(twentyfour(cards))