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C program to remove duplicate nodes from the singly linked list
Here, we are going to learn how to remove duplicate nodes from the singly linked list using C program?
Submitted by Nidhi, on August 23, 2021
Problem Solution:
Given a singly linked list, and we have to remove the duplicate nodes from the linked list.
Program:
The source code to remove duplicate nodes from the singly linked list is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.
// C program to remove duplicate nodes from
// the singly linked list
#include <stdio.h>
#include <stdlib.h>
//Self-referential structure to create the node.
typedef struct tmp {
int item;
struct tmp* next;
} Node;
//structure for creating the linked list.
typedef struct
{
Node* head;
Node* tail;
} List;
//Initialize List
void initList(List* lp)
{
lp->head = NULL;
lp->tail = NULL;
}
//Create node and return the reference of it.
Node* createNode(int item)
{
Node* nNode;
nNode = (Node*)malloc(sizeof(Node));
nNode->item = item;
nNode->next = NULL;
return nNode;
}
//Add a new item at the end of the list.
void addAtTail(List* lp, int item)
{
Node* node;
node = createNode(item);
//if list is empty.
if (lp->head == NULL) {
lp->head = node;
lp->tail = node;
}
else {
lp->tail->next = node;
lp->tail = lp->tail->next;
}
}
//Add a new item at beginning of the list.
void addAtHead(List* lp, int item)
{
Node* node;
node = createNode(item);
//if list is empty.
if (lp->head == NULL) {
lp->head = node;
lp->tail = node;
}
else {
node->next = lp->head;
lp->head = node;
}
}
//To print the list from start to end of the list.
void printList(List* lp)
{
Node* node;
if (lp->head == NULL) {
printf("\nEmpty List");
return;
}
node = lp->head;
while (node != NULL) {
printf("| %05d |", node->item);
node = node->next;
if (node != NULL)
printf("--->");
}
printf("\n\n");
}
void dupDelete(List* lp)
{
Node* current = lp->head;
Node* index;
Node* temp;
while (current != NULL) {
temp = current;
index = current->next;
while (index != NULL) {
if (current->item == index->item)
temp->next = index->next;
else
temp = index;
index = index->next;
}
current = current->next;
}
}
//Main function to execute program.
int main()
{
List* lp;
lp = (List*)malloc(sizeof(List));
initList(lp);
addAtTail(lp, 101);
addAtTail(lp, 102);
addAtTail(lp, 101);
addAtTail(lp, 102);
addAtTail(lp, 105);
printf("List:\n");
printList(lp);
dupDelete(lp);
printf("Updated List:\n");
printList(lp);
return 0;
}
Output:
List:
| 00101 |--->| 00102 |--->| 00101 |--->| 00102 |--->| 00105 |
Updated List:
| 00101 |--->| 00102 |--->| 00105 |
Explanation:
Here, we created a self-referential structure to implement a linked list, a function to add a node at the start and end of the list, and a function dupDelete() to remove duplicate elements.
In the main() function, we created a singly linked list and called the function dupDelete() to remove the duplicate elements. After that, we printed the updated list.