C++ Program For Sorting Linked List Which Is Already Sorted On Absolute Values

// C++ program to sort a linked list, 
// already sorted by absolute values
#include <bits/stdc++.h>
using namespace std;

// Linked List Node
struct Node
{
    Node* next;
    int data;
};

// Utility function to insert a 
// node at the beginning
void push(Node** head, int data)
{
    Node* newNode = new Node;
    newNode->next = (*head);
    newNode->data = data;
    (*head) = newNode;
}

// Utility function to print 
// a linked list
void printList(Node* head)
{
    while (head != NULL)
    {
        cout << head->data;
        if (head->next != NULL)
            cout << " -> ";
        head = head->next;
    }
    cout<<endl;
}

// To sort a linked list by actual values.
// The list is assumed to be sorted by 
// absolute values.
void sortList(Node** head)
{
    // Initialize previous and current 
    // nodes
    Node* prev = (*head);
    Node* curr = (*head)->next;

    // Traverse list
    while (curr != NULL)
    {
        // If curr is smaller than prev, 
        // then it must be moved to head
        if (curr->data < prev->data)
        {
            // Detach curr from linked list
            prev->next = curr->next;

            // Move current node to beginning
            curr->next = (*head);
            (*head) = curr;

            // Update current
            curr = prev;
        }

        // Nothing to do if current 
        // element is at right place
        else
            prev = curr;

        // Move current
        curr = curr->next;
    }
}

// Driver code
int main()
{
    Node* head = NULL;
    push(&head, -5);
    push(&head, 5);
    push(&head, 4);
    push(&head, 3);
    push(&head, -2);
    push(&head, 1);
    push(&head, 0);

    cout << "Original list :";
    printList(head);

    sortList(&head);

    cout << "Sorted list :";
    printList(head);

    return 0;
}