python实现四则元算

这个算法是在阅读大话数据结构中看到的，里面讲到在讲到实现四则元算最好的数据结构是栈；栈遵循后进先出，这与我们做数学题从左到右的认知是一样的。

有兴趣的同学可以去了解下，下面上代码

#coding:utf8
def opNum(data):
    dataSpace = [] 
    lableSpace = [] 
    h = '*,/'
    for i  in data:
        if i  in "-,+,*,/,(,)":
            if i == ")":
                while lableSpace != []:
                    k = lableSpace.pop()
                    if k == "(":
                        break
                    f = dataSpace.pop()
                    s = dataSpace.pop()
                    dataSpace.append(str(eval("%s%s%s"%(s,k,f))))                  
            else:
                if lableSpace != []:
                    p = lableSpace.pop()
                    lableSpace.append(p)
                    if i in h  and  p not in h:
                        lableSpace.append(i)
                    elif i not in h and p in h:
                        while lableSpace != []:
                            f = dataSpace.pop()
                            s = dataSpace.pop()
                            b = lableSpace.pop()
                            dataSpace.append(str(eval("%s%s%s"%(s,b,f))))
                        lableSpace.append(i)  
                    else:                          
                        lableSpace.append(i)
                else:
                    lableSpace.append(i)
        
        else:
            dataSpace.append(i)
    while lableSpace != []:
        f = dataSpace.pop()
        s = dataSpace.pop()
        b = lableSpace.pop()
        dataSpace.append(str(eval("%s%s%s"%(s,b,f))))
    return  int(dataSpace[0])   
    
        
    
            
if __name__=='__main__':
    #data = ['9','+','(','3','-','1',')','*','3','+','10','/','2']
    data = ['3','+','8','-','(','(','3','-','1',')','+','2',')','*','1']
    print opNum(data)