Question

Write a C++ code to ask the user to enter 4 values (whole numbers). Your code should print the numbers in descending order. (Don't solve using array)

Answer 1

In the below code,

1. Take 4 whole numbers as input.

2. Insert these 4 values in the linked list(array cannot be used as directed in the question) as an individual node.

3.Sort the numbers in descending order using insertion sort.

#include<iostream>
using namespace std;

// Link list node
struct Node 
{ 
        int data; 
        struct Node* next; 
}; 

// Function to insert a given node in a reverse sorted linked list 
void descendingSort(struct Node**, struct Node*); 

// function to sort a singly linked list
void insertAtPosition(struct Node **head_ref) 
{ 
        // Initialize sorted linked list 
        struct Node *sorted = NULL; 

        // Traverse the given linked list and insert every node to be sorted 
        struct Node *current = *head_ref; 
        while (current != NULL) 
        { 
                // Store next for next iteration 
                struct Node *next = current->next; 

                // insert current in sorted linked list 
                descendingSort(&sorted, current); 

                // Update current 
                current = next; 
        } 

        // Update head_ref to point to sorted linked list 
        *head_ref = sorted; 
} 

// function to insert a new_node in a list.
void descendingSort(struct Node** head_ref, struct Node* new_node) 
{ 
        struct Node* current; 
        /* Special case for the head end */
        if (*head_ref == NULL || (*head_ref)->data <= new_node->data) 
        { 
                new_node->next = *head_ref; 
                *head_ref = new_node; 
        } 
        else
        { 
                /* Locate the node before the point of insertion */
                current = *head_ref; 
                while (current->next!=NULL && 
                        current->next->data > new_node->data) 
                { 
                        current = current->next; 
                } 
                new_node->next = current->next; 
                current->next = new_node; 
        } 
} 

// Function to print linked list
void printList(struct Node *head) 
{ 
        struct Node *temp = head; 
        while(temp != NULL) 
        { 
                cout<<temp->data<<" "; 
                temp = temp->next; 
        } 
} 

// A function to insert a node at the beginning of linked list
void push(struct Node** head_ref, int new_data) 
{ 
        /* allocate node */
        struct Node* new_node = new Node; 

        /* put in the data */
        new_node->data = new_data; 

        /* link the old list off the new node */
        new_node->next = (*head_ref); 

        /* move the head to point to the new node */
        (*head_ref) = new_node; 
} 

int main() 
{ 
        struct Node *a = NULL;
        int w,x,y,z;
        cin>>w>>x>>y>>z;
        push(&a, w);
        push(&a, x); 
        push(&a, y); 
        push(&a, z); 
        
        cout<<"Linked List before sorting \n"; 
        printList(a); 

        insertAtPosition(&a); 

        cout<<"\nLinked List after sorting \n"; 
        printList(a); 

        return 0; 
} 

OUTPUT :