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 = 100
123+4-5+67-89 = 100
123-45-67+89 = 100
123-4-5-6-7+8-9 = 100
12+3+4+5-6-7+89 = 100
12+3-4+5+67+8+9 = 100
12-3-4+5-6+7+89 = 100
1+23-4+56+7+8+9 = 100
1+23-4+5+6+78-9 = 100
1+2+34-5+67-8+9 = 100
1+2+3-4+5+6+78+9 = 100