1

我的代码有问题。代码给出了一个错误，它说节点在 __add__() 运算符中没有“前一个”，但是它在主程序中没有给出错误分配的重点是创建一个长的使用链表

class Node():
    def __init__(self):
        self.next = None
        self.prev = None
        self.data = None

    def getData(self):
        return self.data

class LinkedList():
    def __init__(self):
        self.count = 0
        self.last = Node()
        self.first = Node()
        self.first.next = self.last
        self.last.previous = self.first

    def append(self, data):
        self.last.data = data
        self.last.next = Node()
        tmp = self.last
        self.last = self.last.next
        self.last.previous = tmp
        self.count += 1

    def prepend(self, data):
        self.first.data = data
        self.first.previous = Node()
        tmp = self.first
        self.first = self.first.previous
        self.first.next = tmp
        self.count += 1

    def front(self):
        if self.count == 0: return None
        return self.first.next

    def back(self):
        if self.count == 0: return None
        return self.last.previous

    def size(self):
        return self.count

    def __getitem__(self, node):
        count = self.first
        while count.data:
            if count.data == node:
                return count
            count = count.next
        return None

    def __iter__(self):
        count = self.first.next
        while count.data:
            print("here")
            yield count.data
            count = count.next

class BigInt:
    def __init__(self, initValue = "0"):
        self.data = LinkedList()
        for count in initValue:
            self.data.append(count)
        self.Neg = False

    def __repr__(self):
        integer = ""
        node = self.data.front()
        while node.next:
            integer= integer+(node.getData())
            node = node.next
        return "".join(integer)

    def toString(self):
        return self.__repr__()

    def isNeg(self):
        return self.Neg

    def __add__(self, rhs):
        node1 = self.data.back()
        node2 = rhs.data.back()
        if self.isNeg() and not rhs.isNeg():
            return rhs - self
        elif rhs.isNeg() and not self.isNeg():
            return self - rhs

        summation = LinkedList()
        carryOne = 0
        print(node1.previous.previous.getData())
        while node1.previous.getData() is not None or node2.previous.getData() is not None:
            tot = int(node1.getData())+int(node2.getData())+carryOne
            summation.prepend((tot)%10)
            carryOne = 0
            if tot >= 10: carryOne = 1
            node1 = node1.previous
            node2 = node2.previous
        ret = ""
        for digit in summation:
            ret = ret + digit
            print(digit)
        print (ret)

    def __sub__():
        pass

a = LinkedList()
a.prepend(4)
a.prepend(5)
a.append(23)
print (type(a.back()))
print(a.back().previous.previous.getData())

g = BigInt("2")
h = BigInt("3")
(g+h)
print (g.toString())
4

1 回答 1

4

previous新建的没有成员Node，只有prev.

的某些实例Node稍后会获得一个名为 的成员previous。这是由于以下代码：

self.last.previous = self.first

（感谢@David Robinson 指出这一点。）

于 2012-11-08T07:28:40.453 回答