# Remove Duplicates from an Unsorted Linked List

Remove Duplicates from an Unsorted Linked List” is one of the foremost problem asked in many technical and algorithmic interviews of product based companies. Here, we are given an unsorted linked list and our task is to remove all duplicate nodes from the given linked list.

Here, we need to take care while removing the duplicate nodes, the order of the nodes must not change.

To do so, we will use two nested loops, outer loop to track current node of the linked list and inner loop to traverse the subsequent linked list and remove every duplicate node with node value as current node by some pointer manipulation.

```For example, we need to remove duplicates from the following unsorted list.
LIST:  45 -> 45 -> 46 -> 56 -> 45 -> 68 -> 46
After removing all the duplicates from an unsorted linked list, the list would become:
LIST: 45 -> 46 -> 56 -> 68```

The steps required to remove duplicates from an unsorted linked list are as follows:

2. Traverse the given linked list with two two loops (nested). The outer loop is used to track the current node of the linked list.
3. Inner traversing loop will used to traverse the subsequent nodes and compare each node element with ‘temp’ node, if the node value matches, then delete that node.

#### C++ Program to remove duplicates from an Unsorted Linked List is as follows:

```/* C++ Program to remove duplicates from an unsorted linked list */
#include<bits/stdc++.h>
using namespace std;

/* Structure of the node of the linked list */
typedef struct node
{
int data;
struct node *next;
}Node;

/* Function to Insert node at the end of the linked list */
{
/* Creating a new node */
Node *new_node;
new_node = (struct node*)malloc(sizeof(struct node));
new_node->data = ele;
new_node->next = NULL;

/* check whether the linked list is empty or not */

/* If Linked List is empty, then new node will become head of the linked list */
{
return;
}
/* If Linked List is not empty, then traverse the complete linked list and point the pointer
of last node of the linked list to the new node */
Node *temp = NULL;
while(temp->next != NULL)
temp=temp->next;
temp->next = new_node;
}

/* Function to remove duplicate Nodes from the linked list */
{
Node *temp = NULL;
/* Outer Loop is used to track current node */
while(curr != NULL)
{
temp = curr;
/* Innser loop is used to delete multiple occurrences of the current node */
while(temp->next != NULL)
{
if(temp->next->data == curr->data)
{
Node *p = temp->next;
temp->next = temp->next->next;
delete p;
}
else
temp = temp->next;
}
curr = curr->next;
}
}

/* Function to Print the Linked List  */
{
while(temp!=NULL)
{
cout<<temp->data<<" ";
temp=temp->next;
}
cout<<endl;
}
int main()
{
/* Inserting Some Nodes in the Linked List */
cout<<"Linked List Before Removing Duplicate Nodes:\n";
cout<<"Linked List After Removing Duplicate Nodes:\n";
```OUTPUT: