Answer to Question #232823 in C++ for xyz

Question

Develop pseudocode of following operations for Doubly Circular Linked List.

i) Insertion of a node at beginning.

ii) Insertion of a node at end.

iii) Deletion of first node.

iv) Deletion of last node.

Answer 1

#include <iostream>
using namespace std;
struct Node {
    int d;
    struct Node* next;
    struct Node* prev;
};


void insert(struct Node** s, int value)
{
    if (*s == NULL) {
        struct Node* new_node = new Node;
        new_node->d = value;
        new_node->next = new_node->prev = new_node;
        *s = new_node;
        return;
    }
 
    Node* last = (*s)->prev;
    struct Node* new_node = new Node;
    new_node->d = value;
    new_node->next = *s;
    (*s)->prev = new_node;
 
    new_node->prev = last;
    last->next = new_node;
}


void deleteNode(struct Node** s, int key)
{
    if (*s == NULL)
        return;
    struct Node *curr = *s, *prev_1 = NULL;
    while (curr->d != key) {
        if (curr->next == *s) {
            printf("\nList doesn't have node with value = %d", key);
            return;
        }
 
        prev_1 = curr;
        curr = curr->next;
    }
 
    if (curr->next == *s && prev_1 == NULL) {
        (*s) = NULL;
        free(curr);
        return;
    }
    if (curr == *s) {
        prev_1 = (*s)->prev;
        *s = (*s)->next;
        prev_1->next = *s;
        (*s)->prev = prev_1;
        free(curr);
    }
    else if (curr->next == *s) {
        prev_1->next = *s;
        (*s)->prev = prev_1;
        free(curr);
    }
    else {
        struct Node* temp = curr->next;
        prev_1->next = temp;
        temp->prev = prev_1;
        free(curr);
    }
}
 
void display(struct Node* s)
{
    struct Node* temp = s;
 
    while (temp->next != s) {
        printf("%d ", temp->d);
        temp = temp->next;
    }
    printf("%d ", temp->d);
}
int main()
{
    struct Node* s = NULL;
     //Insertion of a node at beginning.
    insert(&s, 4);
    insert(&s, 5);
    insert(&s, 6);
    insert(&s, 7);
    //Insertion of a node at end.
    insert(&s, 8);
    
    printf("Before Deletion: ");
    display(s);
    deleteNode(&s, 9);
    
    printf("\nAfter Deletion: ");
    display(s);
    //Deletion of first node.
    deleteNode(&s, 4);
    printf("\nAfter Deleting %d: ", 4);
    display(s);
    //Deletion of last node
    deleteNode(&s, 8);
    printf("\nAfter Deleting %d: ", 8);
    display(s);
    deleteNode(&s, 6);
    printf("\nAfter Deleting %d: ", 6);
    display(s);
 
    return 0;
}