C Program to implement Merge Sort using Linked List

By | 10.10.2016

Merge Sort using Linked List


Write a C Program to implement Merge Sort using Linked List. Here’s simple C Program to implement Merge Sort using Linked List in C Programming Language.


A linked list cannot be accessed randomly and because of this slow access time, sorting algorithms like quick sort cannot be applied to it.

So we use merge sort for this purpose. It works on divide and conquer technique. Time complexity is O(nlogn).


Here is the source code of the C Program to implement Merge Sort using Linked List. The C program is successfully compiled and run(Codeblocks) on a Windows system. The program output is also shown below.


SOURCE CODE : :


/*  C Program to implement Merge Sort using Linked List  */

#include <stdio.h>
#include <stdlib.h>

struct node {
 int number;
 struct node *next;
};

/* add a node to the linked list */
struct node *addnode(int number, struct node *next);
/* preform merge sort on the linked list */
struct node *mergesort(struct node *head);
/* merge the lists.. */
struct node *merge(struct node *head_one, struct node *head_two);

int main(void)
{
 struct node *head;
 struct node *current;
 struct node *next;
 int n,i;

 printf("Enter No. of elements u want to sort : ");
 scanf("%d",&n);

 int test[n];

 printf("Enter elements : \n");
for(i=0;i<n;i++)
{
printf("Enter %d element : ",i+1);
scanf("%d",&test[i]);
}

 head = NULL;
 /* insert some numbers into the linked list */
 for(i = 0; i < n; i++)
  head = addnode(test[i], head);

 /* sort the list */
 head = mergesort(head);

 /* print the list */
 printf(" before  after\n"), i = 0;
 for(current = head; current != NULL; current = current->next)
  printf("%4d\t%4d\n", test[i++], current->number);

 /* free the list */
 for(current = head; current != NULL; current = next)
  next = current->next, free(current);

 /* done... */
 return 0;
}

/* add a node to the linked list */
struct node *addnode(int number, struct node *next) {
 struct node *tnode;

 tnode = (struct node*)malloc(sizeof(*tnode));

 if(tnode != NULL) {
  tnode->number = number;
  tnode->next = next;
 }

 return tnode;
}

/* preform merge sort on the linked list */
struct node *mergesort(struct node *head) {
 struct node *head_one;
 struct node *head_two;

 if((head == NULL) || (head->next == NULL))
  return head;

 head_one = head;
 head_two = head->next;
 while((head_two != NULL) && (head_two->next != NULL)) {
  head = head->next;
  head_two = head->next->next;
 }
 head_two = head->next;
 head->next = NULL;

 return merge(mergesort(head_one), mergesort(head_two));
}

/* merge the lists.. */
struct node *merge(struct node *head_one, struct node *head_two) {
 struct node *head_three;

 if(head_one == NULL)
  return head_two;

 if(head_two == NULL)
  return head_one;

 if(head_one->number < head_two->number) {
  head_three = head_one;
  head_three->next = merge(head_one->next, head_two);
 } else {
  head_three = head_two;
  head_three->next = merge(head_one, head_two->next);
 }

 return head_three;
}

OUTPUT : :


/*  C Program to implement Merge Sort using Linked List  */

Enter No. of elements u want to sort : 7

Enter elements :

Enter 1 element : 5
Enter 2 element : 2
Enter 3 element : 1
Enter 4 element : 4
Enter 5 element : 7
Enter 6 element : 9
Enter 7 element : 0

 before  after
   5       0
   2       1
   1       2
   4       4
   7       5
   9       7
   0       9

Above is the source code for C Program to find area and circumference of circle which is successfully compiled and run on Windows System.The Output of the program is shown above .

If you found any error or any queries related to the above program or any questions or reviews , you wanna to ask from us ,you may Contact Us through our contact Page or you can also comment below in the comment section.We will try our best to reach up to you in short interval.


Thanks for reading the post….

5 1 vote
Article Rating
Category: C Programming Sorting Programs Tags:

About Tunde A

My name is Tunde Ajetomobi, a Tech Enthusiast and Growth Hacker. I enjoy creating helpful content that solves problem across different topics. Codezclub is my way of helping young aspiring programmers and students to hone their skills and find solutions on fundamental programming languages.

Subscribe
Notify of
guest

0 Comments
Inline Feedbacks
View all comments