python实现单链表

# coding:utf-8 


class node: 
    def __init__(self, value): 
        self.data = value 
        self.next = none 


class linklist: 
    def __init__(self, data=[0]): 
        self.head = none 
        self.init_link_list(data) 

    # 初始化链表 
    # data 为数组 
    def init_link_list(self, data): 
        if len(data) == 0: 
            print("initialization data is null") 
            return 
        self.head = node(data[0]) 
        current = self.head 
        for index in data[1:]: 
            current.next = node(index) 
            current = current.next 

    # 获取当前结点 
    def get_node(self, index): 
        if self.is_empty(): 
            print("link is empty") 
            return 
        if index > self.get_length() or index             print("node is not exist") 
            return 
        current = self.head 
        i = 0 
        while i             if i == index - 1: 
                return current 
            current = current.next 
            i += 1 

    # 获取当前元素的值 
    def get_data(self, index): 
        current = self.get_node(index) 
        if current is none: 
            return "node is not exist" 
        return current.data 

    # 打印链表 
    def print_link(self): 
        if self.is_empty(): 
            return 
        list = [] 
        current = self.head 
        while current.next is not none: 
            list.append(current.data) 
            current = current.next 
        else: 
            list.append(current.data) 
        print(list) 

    # 获取链表长度 
    def get_length(self): 
        if self.is_empty(): 
            return 0 
        current = self.head 
        count = 0 
        while current.next is not none: 
            count += 1 
            current = current.next 
        else: 
            count += 1 
        return count 

    # 判断链表是否为空 
    # 如果为空，返回true 
    # 如果不为空，返回false 
    def is_empty(self): 
        return self.head is none 

    # 当前元素之后插入一个元素 
    # index 元素索引 
    # data 插入的值 
    def add_after(self, index, data): 
        current = self.get_node(index) 
        if current is none: 
            return "node is not exist" 
        current_next = current.next 
        current.next = node(data) 
        current = current.next 
        current.next = current_next 

    # 在当前元素之前插入一个元素 
    def add_before(self, index, data): 
        if index == 1: 
            current = self.get_node(index) 
            self.head = node(data) 
            self.head.next = current 
            return 
        pre = self.get_pre_node(index) 
        current = pre.next 
        pre.next = node(data) 
        pre = pre.next 
        pre.next = current 

    # 获取当前元素的前一个元素 
    def get_pre_node(self, index): 
        if self.is_empty(): 
            print("link is empty") 
            return 
        if index > self.get_length() or index             print("node is not exist") 
            return 
        pre = self.head 
        i = 0 
        while i             if i == index - 2: 
                return pre 
            pre = pre.next 
            i += 1 

    # 删除指定元素，并返回删除元素的值 
    def remove(self, index): 
        if index == 1 and not self.is_empty(): 
            data = self.head.data 
            self.head = self.head.next 
            return data 
        pre_node = self.get_pre_node(index) 
        current = self.get_node(index) 
        if pre_node is none or current is none: 
            print("data is not exist") 
        pre_node.next = current.next 
        return current.data 

    # 修改当前结点的值 
    def update(self, index, data): 
        current = self.get_node(index) 
        if current is none: 
            return "current node is none" 
        current.data = data 

    # 将新链表合并到当前链表 
    def merge(self, data): 
        size = self.get_length() 
        last_node = self.get_node(size) 
        last_node.next = data.head 
        return self 

# test 
y = (1,2,3,4) 
s = ["a", "b", "c", "d"] 
linklist = linklist(y) 
# linklist.init_link_list(["a", "b", "c", "d"]) 
# second = linklist() 
# second.init_link_list(["x", "y", "z"]) 
# linklist.add_after(-1, "x") 
# linklist.add_after(1, "y") 
# linklist.init_link_list([]) 
# linklist.add_before(1,"x") 
# linklist.print_link() 
# print("item:", linklist.get_data(2)) 
# print("length:", linklist.get_length()) 
# print("is empty", linklist.is_empty()) 
# print(linklist.get_pre_node(3).data) 
# print("remove node:",linklist.remove(2)) 
# linklist.merge(second) 


linklist.print_link()