c code to swap pair of elements of a linked list
write a c code to swap pair of elements of a linked list
Write a program to swap pair of elements of a linked list of n integers from starting. If n is odd, then the last number will remain unchanged.
Code
#include <stdio.h>
#include <malloc.h>
struct node
{
int data;
struct node *next;
};
struct node *head, *tail = NULL;
void addNode(int data)
{
struct node *newNode = (struct node *)malloc(sizeof(struct node));
newNode->data = data;
newNode->next = NULL;
if (head == NULL)
{
head = newNode;
tail = newNode;
}
else
{
tail->next = newNode;
tail = newNode;
}
}
void swap(int n1, int n2)
{
struct node *prevNode1 = NULL, *prevNode2 = NULL, *node1 = head, *node2 = head, *temp = NULL;
if (head == NULL)
{
return;
}
if (n1 == n2)
return;
while (node1 != NULL && node1->data != n1)
{
prevNode1 = node1;
node1 = node1->next;
}
while (node2 != NULL && node2->data != n2)
{
prevNode2 = node2;
node2 = node2->next;
}
if (node1 != NULL && node2 != NULL)
{
if (prevNode1 != NULL)
prevNode1->next = node2;
else
head = node2;
if (prevNode2 != NULL)
prevNode2->next = node1;
else
head = node1;
temp = node1->next;
node1->next = node2->next;
node2->next = temp;
}
else
{
printf("Swapping is not possible\n");
}
}
void display()
{
struct node *current = head;
if (head == NULL)
{
printf("List is empty\n");
return;
}
while (current != NULL)
{
printf("%d-->", current->data);
current = current->next;
}
printf("NULL\n");
}
int main()
{
addNode(1);
addNode(2);
addNode(3);
addNode(4);
addNode(5);
printf("Original list: \n");
display();
swap(1, 4);
swap(2, 3);
printf("List after swapping nodes: \n");
display();
return 0;
}