Python实现1-9数组形成的结果为100的所有运算式

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