python 数据结构与算法 day01 单链表

1. 实现单链表：

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

class SingleLinkList(object):
    def __init__(self,node=None):
        self.__head=node

    def is_empty(self):
        """判断链表是否为空"""
        return self.__head==None
    def length(self):
        """求链表的长度（需要特别考虑链表为空的情况）"""
        cursor=self.__head  # 游标,实现单链表的遍历（不断移动cursor指针的位置）
        count=0
        while cursor!=None:
            count+=1
            cursor=cursor.next
        return count
    def travel(self):
        """实现单链表的遍历"""
        cursor=self.__head
        while cursor!=None:
            print(cursor.item)
            cursor=cursor.next
    def append(self,item):
        """往单链表尾部追加元素"""
        node=Node(item)
        cursor=self.__head
        if self.is_empty():
            self.__head=node
        else:
            while cursor.next!=None:
                cursor=cursor.next
            cursor.next=node

ssl=SingleLinkList()
print(ssl.is_empty())
print(ssl.length())
ssl.append(1)
ssl.append(2)
ssl.append(3)
ssl.append(4)
print(ssl.length())
ssl.travel()

运行结果：

2. 实现单链表（完整版）

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

class SingleLinkList(object):
    def __init__(self,node=None):
        self.__head=node

    def is_empty(self):
        """判断链表是否为空"""
        return self.__head==None
    def length(self):
        """求链表的长度（需要特别考虑链表为空的情况）"""
        cursor=self.__head  # 游标,实现单链表的遍历（不断移动cursor指针的位置）
        count=0
        while cursor!=None:
            count+=1
            cursor=cursor.next
        return count
    def travel(self):
        """实现单链表的遍历"""
        cursor=self.__head
        while cursor!=None:
            print(cursor.item,end=" ")
            cursor=cursor.next
    def append(self,item):
        """往单链表尾部追加元素(尾插法)"""
        node=Node(item)
        cursor=self.__head
        if self.is_empty():
            self.__head=node
        else:
            while cursor.next!=None:
                cursor=cursor.next
            cursor.next=node
    def add(self,item):
        """在单链表头部插入元素（头插法）"""
        node=Node(item)
        node.next=self.__head
        self.__head=node
    def insert(self,pos,item):
        """在单链表任意位置插入元素"""
        count=0
        cursor=self.__head
        node=Node(item)
        if self.__head==None:
            node.next=self.__head
            self.__head=node
        else:
            while count!=pos-2:
                cursor=cursor.next
                count+=1
            node.next=cursor.next
            cursor.next=node
    def remove(self,item):
        """删除一个节点中元素"""
        cur_left=self.__head
        if not self.is_empty():
            if self.__head.next==None:  # 单链表长度为1
                if self.__head.item == item:  # 删除第一个节点
                    self.__head = None
                else:
                    return
            else:
                if self.__head.item==item:  # 删除第一个节点
                    self.__head=self.__head.next
                    return
                cur_right=cur_left.next
                while cur_right!=None:
                    if cur_right.item==item:
                        if cur_right.next==None:  # 删除最后一个节点
                            self.cur_left.next=None
                            return
                        else:
                            cur_left.next=cur_right.next
                            return
                    else:
                        cur_left=cur_left.next
                        cur_right=cur_right.next







ssl=SingleLinkList()
print(ssl.is_empty())
print(ssl.length())
ssl.append(1)
ssl.append(2)
ssl.append(3)
ssl.append(4)
ssl.add(0)
ssl.insert(2,2000)

print(ssl.length())
ssl.travel()

ssl.remove(2000)
print("
")
ssl.travel()

运行结果：

开森~