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#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;
struct node
{
int data;
struct node* next;
};
typedef struct node* nodePtr;
nodePtr curr;
nodePtr temp;
nodePtr head;
nodePtr Node;
struct node* SortedMerge(node* a, node* b);
void SplitFrontnBack(node* givennumber, node** Front, node** Back);
void display();
bool Empty() {
return head == NULL;
}
void addNode(int data ){
nodePtr n = new node;
n->next = NULL;
n->data = data;
if(!Empty()){
curr = head;
while(curr->next !=NULL){
curr = curr->next;
}
curr->next = n;
}
else{
head = n;
}
}
int calculateSize()
{
int count = 0;
Node= head;
while(Node!=NULL){
count++;
Node = Node->next;
}
return count;
}
void display(node * node){
while(node != NULL)
{
cout<<node->data<<" ";
node = node-> next;
}
cout<<endl;
}
/* sorts the linked list by changing next pointers (not data) */
void MergeSort(struct node** Head)
{
node* head = *Head;
node* a;
node* b;
if ((head == NULL) || (head->next == NULL))
{
return;
}
SplitFrontnBack(head, &a, &b);
MergeSort(&a);
MergeSort(&b);
*Head = SortedMerge(a, b);
}
/* merge the sorted linked lists */
node* SortedMerge(struct node* a, struct node* b)
{
node* result = NULL;
if (a == NULL)
return b;
else if (b==NULL)
return a;
if (a->data <= b->data)
{
result = a;
result->next = SortedMerge(a->next, b);
}
else
{
result = b;
result->next = SortedMerge(a, b->next);
}
return result;
}
/* Split the nodes of the given list into front and back halves*/
void SplitFrontnBack(node* givennumber, node** Front, node** Back)
{
node* fast;
node* slow;
if (givennumber==NULL || givennumber->next==NULL)
{
*Front = givennumber;
*Back = NULL;
}
else
{
slow = givennumber;
fast = givennumber->next;
while (fast != NULL)
{
fast = fast->next;
if (fast != NULL)
{
slow = slow->next;
fast = fast->next;
}
}
*Front = givennumber;
*Back = slow->next;
slow->next = NULL;
}
}
void push(node** head_ref, int new_data)
{
node *new_node = new node;
new_node->data = new_data;
new_node->next = (*head_ref);
(*head_ref) = new_node;
}
/* Main */
int main()
{
node* res = NULL;
node* a = NULL;
push(&a, 15);
push(&a, 10);
push(&a, 5);
push(&a, 20);
push(&a, 3);
push(&a, 2);
MergeSort(&a);
cout<<"\n Sorted Linked List is: \n";
display(a);
return 0;
}
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