python数据结构之单链表

单链表的操作

1、is_empty()链表是否为空
2、length()链表的长度
3、add()链表的头部添加元素
4、append()链表尾部添加元素
5、insert()指定位置添加元素
6、remove()删除节点
7、search()查找链表是否存在

源代码

class Node():
    """节点"""
    def __init__(self,data = None):
        self.elem = data                #节点中的数据
        self.next = None                #下一个地址（元组也可以实现）

class singleLinkedLists(object):
    """单链表的实现"""
    #创建头结点
    def __init__(self, node = None):
        self.__head = node

    def isEmpty(self):
        """链表是否为空"""
        return self.__head == None

    def length(self):
        """链表的长度"""
        cur = self.__head
        if self.__head == None:
            return 0
        else:
            count = 1
            while cur.next != None:
                count += 1
                cur = cur.next
            return count

    def travel(self):
        """遍历链表"""
        cur = self.__head
        if self.__head == None:
            return "空链表"
        else:
            while cur.next != None:
                print(cur.elem,end=" ")
                cur = cur.next
            print(cur.elem)

    def append(self, data):
        """链表尾部添加元素(尾插法)"""
        node = Node(data)
        if self.__head == None:
            self.__head = node
        else:
            cur = self.__head
            while cur.next != None:
                cur = cur.next
            cur.next = node

    def insert(self,pos,data):      #pos表示插入位置，item表示插入数据
        """指定位置添加元素
        :param pos 从1开始
        """
        if pos < 1:
            self.add(data)
            return
        elif pos > self.length():
            self.append(data)
            return
        count = 1  #count用来记录位置
        cur = self.__head
        node = Node(data)
        if pos == 1:
            node.next = self.__head
            self.__head = node
        else:
            while cur.next != None:
                if count == pos - 1:
                    node.next = cur.next
                    cur.next = node
                    break
                count += 1
                cur = cur.next

    def add(self,data):
        """在头部添加元素（头插法）"""
        node = Node(data)
        if self.__head == None:
            self.__head = node
        else:
            node.next = self.__head
            self.__head = node

    def remove(self,data):
        """删除节点(删除具体数据，有多个全部删除)"""
        cur = self.__head
        pre = None
        while cur != None:
            if cur.elem == data:
                #判断是否头结点
                if cur == self.__head:
                    self.__head = cur.next
                else:
                    pre.next = cur.next
                    pre = cur
                    cur = cur.next
            else:
                pre = cur
                cur = cur.next

    def search(self,data):
        """查找链表是否存在"""
        cur = self.__head
        while cur != None:
            if cur.elem == data:
                return "该数据存在于链表中"
            else:
                cur = cur.next
        return "该数据不存在于链表中"

if __name__ == '__main__':
    #以下为测试用例
    sll = singleLinkedLists()
    #print(sll.is_empty())
    #print(sll.length())
    node = Node(100)
    ll = singleLinkedLists()
    for i in range(1,10):
        ll.append(i)
    for j in range(100,109):
        ll.add(j)
    print(ll.insert(-1,633))
    print(ll.remove(9))
    print(ll.travel())
    print("*************")
    print(ll.length())
    print(ll.search(693))