Python程序：搜索循环链表中的元素

当需要在循环链表中搜索某个元素时，需要创建一个“节点”类。该类有两个属性，即节点中的数据以及链表中下一个节点的访问方式。

在循环链表中，头部和尾部是相邻的。它们连接在一起形成一个圆，并且最后一个节点没有“NULL”值。另一个类需要被创建，它包含一个初始化函数，头节点将被初始化为“None”。

用户定义多个方法来添加节点到连接列表中，搜索连接列表中的特定节点以及打印节点值。

下面是一个示例:

示例

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

class list_creation:
   def __init__(self):
      self.head = Node(None)
      self.tail = Node(None)
      self.head.next = self.tail
      self.tail.next = self.head
   def add_data(self,my_data):
      new_node = Node(my_data)
      if self.head.data is None:
         self.head = new_node
         self.tail = new_node
         new_node.next = self.head
      else:
         self.tail.next = new_node
         self.tail = new_node
         self.tail.next = self.head
   def search_value(self,elem_to_search):
      curr = self.head;
      i = 1;
      flag_val = False;
      if(self.head == None):
         print("The list is empty");
      else:
         while(True):
            if(curr.data == elem_to_search):
               flag_val = True;
               break;
            curr = curr.next;
            i = i + 1;
            if(curr == self.head):
               break;
         if(flag_val):
            print("The element is present in list at position : " + str(i));
         else:
            print("The element is not present in list");
   def print_it(self):
      curr = self.head
      if self.head is None:
         print("The list is empty");
         return;
      else:
         print(curr.data)
         while(curr.next != self.head):
            curr = curr.next
            print(curr.data)
         print("\n")

class circular_linked_list:
   my_cl = list_creation()
   print("Nodes are being added to the list")
   my_cl.add_data(21)
   my_cl.add_data(54)
   my_cl.add_data(78)
   my_cl.add_data(99)
   my_cl.add_data(27)
   print("The list is :")
   my_cl.print_it()
   print("Value 99 is being searched")
   my_cl.search_value(99)
   print("Value 0 is being searched")
   my_cl.search_value(0)

输出

Nodes are being added to the list
The list is :
21
54
78
99
27
Value 99 is being searched
The element is present in list at position : 4
Value 0 is being searched
The element is not present in list