Inserting a Node Into a Sorted Doubly Linked List
Problem Statement :
Given a reference to the head of a doubly-linked list and an integer ,data , create a new DoublyLinkedListNode object having data value data and insert it at the proper location to maintain the sort. Example head refers to the list 1 <-> 2 <-> 4 - > NULL. data = 3 Return a reference to the new list: 1 <-> 2 <-> 4 - > NULL , Function Description Complete the sortedInsert function in the editor below. sortedInsert has two parameters: DoublyLinkedListNode pointer head: a reference to the head of a doubly-linked list int data: An integer denoting the value of the data field for the DoublyLinkedListNode you must insert into the list. Returns DoublyLinkedListNode pointer: a reference to the head of the list Note: Recall that an empty list (i.e., where head = NULL ) and a list with one element are sorted lists. nput Format The first line contains an integer t, the number of test cases. Each of the test case is in the following format: The first line contains an integer n, the number of elements in the linked list. Each of the next n lines contains an integer, the data for each node of the linked list. The last line contains an integer, data , which needs to be inserted into the sorted doubly-linked list.
Solution :
Solution in C :
In C++ :
/*
Insert Node in a doubly sorted linked list
After each insertion, the list should be sorted
Node is defined as
struct Node
{
int data;
Node *next;
Node *prev
}
*/
Node* SortedInsert(Node *head,int data)
{
// Complete this function
// Do not write the main method.
Node *current = NULL;
Node *new_node = (Node*)malloc(sizeof(Node));
new_node->data=data;
new_node->next=NULL;
new_node->prev=NULL;
if (head == NULL )
{
head = new_node;
}
else if(head->data >= new_node->data)
{
new_node->next = head;
head->prev=new_node;
head = new_node;
}
else
{
current = head;
while (current->next!=NULL && current->next->data < new_node->data)
{
current = current->next;
}
if(current->next!=NULL)
{
new_node->next = current->next;
current->next->prev=new_node;
}
current->next = new_node;
new_node->prev=current;
}
return head;
}
In Java :
/*
Insert Node at the end of a linked list
head pointer input could be NULL as well for empty list
Node is defined as
class Node {
int data;
Node next;
Node prev;
}
*/
Node SortedInsert(Node head,int data) {
Node n= new Node();
n.data=data;
n.next=null;
n.prev=null;
if(head==null)
return n;
if(head.data > data)
{
n.next=head;
head.prev=n;
return n;
}
Node temp=head;
while(temp.next!=null)
{
if(temp.next.data > data)
{
n.next=temp.next;
n.prev=temp.next.prev;
temp.next=n;
n.next.prev=n;
return head;
}
temp=temp.next;
}
temp.next=n;
n.prev=temp;
return head;
}
In python3 :
"""
Insert a node into a sorted doubly linked list
head could be None as well for empty list
Node is defined as
class Node(object):
def __init__(self, data=None, next_node=None, prev_node = None):
self.data = data
self.next = next_node
self.prev = prev_node
return the head node of the updated list
"""
def SortedInsert(head, data):
new = Node(data=data)
tmp = head
while tmp.data <= data and tmp.next != None and tmp.next.data <= data:
tmp = tmp.next
new.prev = tmp
new.next = tmp.next
tmp.next = new
if new.next != None:
new.next.prev = new
return head
In C :
// Complete the sortedInsert function below.
/*
* For your reference:
*
* DoublyLinkedListNode {
* int data;
* DoublyLinkedListNode* next;
* DoublyLinkedListNode* prev;
* };
*
*/
DoublyLinkedListNode* sortedInsert(DoublyLinkedListNode* head, int data) {
DoublyLinkedListNode *New = create_doubly_linked_list_node(data);
if (!head)
{
head = New;
return head;
}
else if (data < (head->data))
{
New->next = head;
head->prev = New;
New->prev = NULL;
head = New;
return head;
}
else
{
DoublyLinkedListNode *temp = head;
while ( ((temp->next) != NULL) && ((temp->next->data) <= data))
temp = temp->next;
if (temp->next != NULL)
{
DoublyLinkedListNode *next = temp->next;
next->prev = New;
New->next = next;
}
else
New->next = NULL;
temp->next = New;
New->prev = temp;
}
return head;
}
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