给定一个仅包含0-9的字符串和一个目标值，返回在数字之间添加了二元运算符(不是一元的) +、-或*之后所有能得到目标值的情况。

例如:

"123", 6 -> ["1+2+3", "1*2*3"] "232", 8 -> ["2*3+2", "2+3*2"]"105", 5 -> ["1*0+5","10-5"]"00", 0 -> ["0+0", "0-0", "0*0"]"3456237490", 9191 -> []

#coding=utf-8import itertoolsimport reclass Solution(object):    def addOperators(self, num, target):        if num:            count = len(num)-1            rnum = num[-1]            s = "['','+','-','*'],"            ss = ""            for c in range(count):                ss += s            ls = []              for item in itertools.product(*eval(ss[0:-1])):                zty = ''.join(list(itertools.chain.from_iterable(zip(list(num),item))))+rnum                if eval(zty) != target or re.match(r".*([\+\-\*]0)\d.*",zty,re.M|re.I):                    continue                else:                    ls.append(zty)            return ls        return []            print Solution().addOperators("105", 5)