Linked List Swap Two nodes, getting segmentation fault

/* Given a Linked List you are supposed to swap two nodes The values of two nodes are say i and j */ #include<bits/stdc++.h> using namespace std; // strcuture for a singly List Node struct node { int value; struct node *next; }; void swap( struct node *head, int i, int j ){ if( head == NULL || head -> next == NULL ){ cout << "Cannot be swapped" << endl; } else{ struct node *p = head; struct node *q = head; while( p -> next -> value != i ){ p = p -> next; } while( q -> next -> value != j ){ q = q -> next; } struct node *first = p -> next; struct node *second = q -> next; struct node *temp = second -> next; p -> next = second; second -> next = q; q -> next = first; first -> next = temp; } } #include <bits/stdc++.h> using namespace std; // function definition for head node of the LL node *CreateHeadNode(int data) { struct node *head = (struct node *)malloc(sizeof(struct node)); head->value = data; head->next = NULL; return head; } // function definition for other nodes of the LL node *CreateNode(int data) { struct node *temp = (struct node *)malloc(sizeof(struct node)); temp->value = data; temp->next = NULL; return temp; } // print the Linked List void printLL(struct node *head) { struct node *temp = head; while (temp != NULL) { cout << temp->value << " "; temp = temp->next; } } // main function int main(void) { int n; // No. of elements of LinkedList cout << "Enter the no. of elements of LinkedList"; cin >> n; // declaring an array int arr[n]; // reading array elements for (int i = 0; i < n; ++i) { cin >> arr[i]; } // creating head node struct node *head = CreateHeadNode(arr[0]); /* A temporary pointer pointing to start of the LL i.e head position. It is a general assumption that we are not supposed to alter the head pointer of the LL as we may loose the track of the starting address of the Linkedlist */ struct node *temp = head; // creating the further LL for (int i = 1; i < n; ++i) { struct node *ptr = CreateNode(arr[i]); temp->next = ptr; temp = ptr; } printLL(head); swap( head, arr[2], arr[5] ); printLL(head); }