[数据结构与算法]2 Python链表

单链表类的定义

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

头插法添加元素

• 先生成新结点

遍历单链表

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

class List(object):
    '''创建一个单链表类'''
    def __init__(self):
        '''初始化单链表'''
        self.__head = None # 表头，head为空

    def is_empty(self):
        if self.__head:
            return 1
        else:
            return 0
       def add(self, item):
        '''头插法'''
        s = Node(item) # 生成新节点
        s.next = self.__head
        self.__head = s

    def travel(self):
        '''遍历单恋表'''
        p = self.__head  # 定义指针p，p从表头开始
        while p != None:
            print(p.data, end='')
            p = p.next  # 指针移动到下一元素

尾插法

• 先把指针移动到最后一个节点
• 创建一个节点
• 把新结点的地址放在最后一个节点的指针域里

指定位置插入元素insert(self, pos, x)

按值删除元素

单链表增删查改完整代码python

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

class List(object):
    '''创建一个单链表类'''
    def __init__(self):
        '''初始化单链表'''
        self.__head = None # 表头，head为空

    def is_empty(self):
        if self.__head:
            return 1
        else:
            return 0

    def add(self, item):
        '''头插法'''
        s = Node(item) # 生成新节点
        s.next = self.__head
        self.__head = s

	    def add(self, item):
        '''头插法'''
        s = Node(item) # 生成新节点
        s.next = self.__head
        self.__head = s

    def add_end(self, x):
        '''尾插法'''
        s = Node(x)
        p = self.__head
        if self.__head == None:
            self.__head = s
        else:
            while p.next != None:
                p = p.next
            p.next = s

    def insert(self, pos, x):
        '''指定位置插入元素'''
        p = self.__head
        count = 0
        if pos >= self.length():
            return -1
        while count < pos:
            p = p.next
            count += 1
        s = Node(x)
        s.next = p.next
        p.next = s
        return 1

    def remove(self, item):
        p = self.__head
        if p.data == item:
            self.__head = p.next
        else:
            while p!=None and p.data!=item:
                pre = p
                p = p.next
            pre.next = p.next


    def travel(self):
        '''遍历单恋表'''
        p = self.__head  # 定义指针p，p从表头开始
        while p != None:
            print(p.data, end=' ')
            p = p.next  # 指针移动到下一元素
        print('\n')
                                                                                                 def length(self):
        p = self.__head
        count = 0
        while p != None:
            count +=1
            p = p.next
        return count

    def search_pos(self, pos):
        '''按序号查找，pos是待查找的位置'''
        p = self.__head
        count = 1  # 计数器
        if pos < 1:  # 判断位置是否合法
            return None
        else:
            while p != None and count != pos:
                p = p.next
                count += 1
            return p   # 成功返回节点p

    def search_value(self, value):
        '''search a item by value'''
        p = self.__head
        while p!=None and p.data!=value:
            p = p.next

        if p.data == value:
            return p

        elif p == None:
            return None