py003 -双向链表的Python实现

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Code:

class Node(object): 
    """结点"""
    def __init__(self, item):
        self.elem = item
        self.next = None
        self.prev = None

class DoubleLinklist(object):
    """双链表"""
    def __init__(self, node = None):
        self.__head = node

    def is_empty(self):
        """判断单链表是否为空"""
        return self.__head is None

    def length(self):
        """单链表长度"""
        cur = self.__head  # 设置游标cur
        count = 0  # 设置计数器
        while cur != None:
            count += 1
            cur = cur.next
        return count

    def travel(self):
        """遍历单链表"""
        cur = self.__head  # 设置游标cur
        while cur != None:
            print(cur.elem, end=" ")
            cur = cur.next
        print()

    def add(self, elem):
        """在头部添加结点"""
        node = Node(elem)
        if self.is_empty():
            self.__head = node
            print("空表头部添加成功")
        else:
            node.next = self.__head
            self.__head.prev = node
            self.__head = node
            print("头部" + str(elem) + "添加成功")

    def append(self, elem):
        """在尾部添加结点"""
        node = Node(elem)
        if self.is_empty():
            self.__head = node
            print("空表尾部添加"+ str(elem) +"成功！")
        else:
            cur = self.__head
            while cur.next != None:
                cur = cur.next
            cur.next = node
            node.prev = cur
            print("尾部添加"+ str(elem) +"成功！")

    def insert(self, pos, elem):
        node = Node(elem)
        if pos <= 0:
            self.add(elem)
        elif pos > (self.length()-1):
            self.append(elem)
        else:
            cur = self.__head
            count = 0
            while count < pos-1:
                cur = cur.next
                count += 1
            cur.next.prev = node
            node.next = cur.next
            node.prev = cur
            cur.next = node
        print("添加成功！")
        
    def remove(self, elem):
        """删除双链表第一个elem结点"""
        if self.is_empty():
            print("SingleLinklist is none!")
            return False
        cur = self.__head
        pre = None
        mark = False
        while cur != None:
            if cur.elem != elem:
                pre = cur
                cur = cur.next
            else:
                mark = True
                if cur == self.__head:  
                    # 头节点要特殊处理
                    self.__head = self.__head.next
                    self.__head.prev = None
                    cur = self.__head
                else:
                    pre.next = cur.next
                    cur.next.prev = pre
                    cur = cur.next
        print(mark)  # 显示是否删除成功

    def search(self, elem):
        """查找某一元素"""
        if self.is_empty():
            return False
        cur = self.__head
        count = 0 
        while cur != None:
            if cur.elem == elem:
                return count 
            cur = cur.next
            count += 1
        return False
        

if __name__ == "__main__":
    li2 = DoubleLinklist()
    li2.travel()
    li2.append(7)
    li2.append(8)
    li2.append(9)
    li2.travel()
    li2.add(5)
    li2.add(4)
    li2.add(3)
    li2.add(2)
    li2.add(1)
    li2.add(0)
    li2.travel()
    print("查找成功:" + str(li2.search(8)))
    li2.insert(6, 6)
    li2.travel()
    li2.remove(7)
    li2.travel()
    print("OVER")

OUTPUT