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Python Linked List: Search a specific item in a given doubly linked list and return true if the item is found otherwise return false

Python Linked List: Exercise-13 with Solution

Write a Python program to search a specific item in a given doubly linked list and return true if the item is found otherwise return false.

Sample Solution:-

Python Code:

class Node(object):
    # Singly linked node
    def __init__(self, data=None, next=None, prev=None):
        self.data = data
        self.next = next
        self.prev = prev

class doubly_linked_list(object):
    def __init__(self):
        self.head = None
        self.tail = None
        self.count = 0

    def append_item(self, data):
        # Append an item 
        new_item = Node(data, None, None)
        if self.head is None:
            self.head = new_item
            self.tail = self.head
        else:
            new_item.prev = self.tail
            self.tail.next = new_item
            self.tail = new_item
        self.count += 1
    
    def iter(self):
        # Iterate the list
        current = self.head
        while current:
            item_val = current.data
            current = current.next
            yield item_val

    def print_foward(self):
        for node in self.iter():
            print(node)   
        
    def search_item(self, val):
         for node in self.iter():
            if val == node:
                return True
         return False

items = doubly_linked_list()
items.append_item('PHP')
items.append_item('Python')
items.append_item('C#')
items.append_item('C++')
items.append_item('Java')
items.append_item('SQL')

print("Original list:")
items.print_foward()
print("\n")
if items.search_item('SQL'):
    print("True")
else:
    print("False")

if items.search_item('C+'):
    print("True")
else:
    print("False")

Sample Output:

Original list:
PHP
Python
C#
C++
Java
SQL


True
False

Flowchart:

Flowchart: Search a specific item in a given doubly linked list and return true if the item is found otherwise return false.

Python Code Editor:

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Previous: Write a Python program to insert an item in front of a given doubly linked list.
Next: Write a Python program to delete a specific item from a given doubly linked list.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m