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 <= 0:
print("node is not exist")
return
current = self.head
i = 0
while i < index:
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 <= 1:
print("node is not exist")
return
pre = self.head
i = 0
while i < index:
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()