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Python Linked List: Delete the first item from a singly linked list

Python Linked List: Exercise-6 with Solution

Write a Python program to delete the first item from a singly linked list.

Sample Solution:-

Python Code:

class Node:
    # Singly linked node
    def __init__(self, data=None):
        self.data = data
        self.next = None
class singly_linked_list:
    def __init__(self):
        # Createe an empty list
        self.tail = None
        self.head = None
        self.count = 0

    def append_item(self, data):
        #Append items on the list
        node = Node(data)
        if self.head:
            self.head.next = node
            self.head = node
        else:
            self.tail = node
            self.head = node
        self.count += 1
    
    def delete_item(self, data):
        # Delete an item from the list
        current = self.tail
        prev = self.tail
        while current:
            if current.data == data:
                if current == self.tail:
                    self.tail = current.next
                else:
                    prev.next = current.next
                self.count -= 1
                return
            prev = current
            current = current.next
    def iterate_item(self):
        # Iterate the list.
        current_item = self.tail
        while current_item:
            val = current_item.data
            current_item = current_item.next
            yield val

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

print("Original list:")
for val in items.iterate_item():
    print(val)

print("\nAfter removing the first item from the list:")
items.delete_item('PHP')
for val in items.iterate_item():
    print(val)

Sample Output:

Original list:
PHP
Python
C#
C++
Java

After removing the first item from the list:
Python
C#
C++
Java

Flowchart:

Flowchart: Delete the first item from a singly linked list.

Python Code Editor:

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Next: Write a Python program to delete the last item from a singly linked list.

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Python: Tips of the Day

Creates a dictionary with the same keys as the provided dictionary and values generated by running the provided function for each value:

Example:

def tips_map_values(obj, fn):
  ret = {}
  for key in obj.keys():
    ret[key] = fn(obj[key])
  return ret
users = {
  'Owen': { 'user': 'Owen', 'age': 29 },
  'Eddie': { 'user': 'Eddie', 'age': 15 }
}

print(tips_map_values(users, lambda u : u['age'])) # {'Owen': 29, 'Eddie': 15}

Output:

{'Owen': 29, 'Eddie': 15}