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@zjplab
Created February 20, 2017 13:32
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Deleting a node in a linkedlist
// A complete working C program to demonstrate deletion in singly
// linked list
#include <stdio.h>
#include <stdlib.h>
// A linked list node
struct node
{
int data;
struct node *next;
};
/* Given a reference (pointer to pointer) to the head of a list
and an int, inserts a new node on the front of the list. */
void push(struct node** head_ref, int new_data)
{
struct node* new_node = (struct node*) malloc(sizeof(struct node));
new_node->data = new_data;
new_node->next = (*head_ref);
(*head_ref) = new_node;
}
/* Given a reference (pointer to pointer) to the head of a list
and a key, deletes the first occurrence of key in linked list */
void deleteNode(struct node **head_ref, int key)
{
// Store head node
struct node* temp = *head_ref, *prev;
// If head node itself holds the key to be deleted
if (temp != NULL && temp->data == key)
{
*head_ref = temp->next; // Changed head
free(temp); // free old head
return;
}
// Search for the key to be deleted, keep track of the
// previous node as we need to change 'prev->next'
while (temp != NULL && temp->data != key)
{
prev = temp;
temp = temp->next;
}
// If key was not present in linked list
if (temp == NULL) return;
// Unlink the node from linked list
prev->next = temp->next;
free(temp); // Free memory
}
// This function prints contents of linked list starting from
// the given node
void printList(struct node *node)
{
while (node != NULL)
{
printf(" %d ", node->data);
node = node->next;
}
}
/* Drier program to test above functions*/
int main()
{
/* Start with the empty list */
struct node* head = NULL;
push(&head, 7);
push(&head, 1);
push(&head, 3);
push(&head, 2);
puts("Created Linked List: ");
printList(head);
deleteNode(&head, 1);
puts("\nLinked List after Deletion of 1: ");
printList(head);
return 0;
}
# Node class
class Node:
# Constructor to initialize the node object
def __init__(self, data):
self.data = data
self.next = None
class LinkedList:
# Function to initialize head
def __init__(self):
self.head = None
# Function to insert a new node at the beginning
def push(self, new_data):
new_node = Node(new_data)
new_node.next = self.head
self.head = new_node
# Given a reference to the head of a list and a key,
# delete the first occurence of key in linked list
def deleteNode(self, key):
# Store head node
temp = self.head
# If head node itself holds the key to be deleted
if (temp is not None):
if (temp.data == key):
self.head = temp.next
temp = None
return
# Search for the key to be deleted, keep track of the
# previous node as we need to change 'prev.next'
while(temp is not None):
if temp.data == key:
break
prev = temp
temp = temp.next
# if key was not present in linked list
if(temp == None):
return
# Unlink the node from linked list
prev.next = temp.next
temp = None
# Utility function to print the linked LinkedList
def printList(self):
temp = self.head
while(temp):
print " %d" %(temp.data),
temp = temp.next
# Driver program
llist = LinkedList()
llist.push(7)
llist.push(1)
llist.push(3)
llist.push(2)
print "Created Linked List: "
llist.printList()
llist.deleteNode(1)
print "\nLinked List after Deletion of 1:"
llist.printList()
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