Python实现1-9数组形成的结果为100的所有运算式的示例

from functools import reduce operator = {  1: '+',  2: '-',  0: '' }  base = ['1', '2', '3', '4', '5', '6', '7', '8', '9']  def isHundred(num):   #转化为8位3进制数，得到运算符数组  arr = []  for index in range(8):   index = 7 - index   arr.append(num // (3 ** index))   num -= (num // (3 ** index)) * (3 ** index)  arr = map(lambda x: operator[x], arr)   #合并得到运算式  formula = reduce(lambda x, y: x + y, zip(base, arr))   formula = list(formula)  formula.append('9')   formula = ''.join(formula)  #计算运算式结果  res = eval(formula)  return res, formula   if __name__ == '__main__':  #所有可能的结果  total = 3 ** 8 for i in range(total):   res, formula = isHundred(i)   if res == 100:    print(formula+' = 100')

/usr/bin/python3.5 /home/kang/workspace/Qt3d/test.py 123+45-67+8-9 = 100123+4-5+67-89 = 100123-45-67+89 = 100123-4-5-6-7+8-9 = 10012+3+4+5-6-7+89 = 10012+3-4+5+67+8+9 = 10012-3-4+5-6+7+89 = 1001+23-4+56+7+8+9 = 1001+23-4+5+6+78-9 = 1001+2+34-5+67-8+9 = 1001+2+3-4+5+6+78+9 = 100