C Programming Code Examples

C > Linked Lists Code Examples

Find Number of Occurrences of All Elements in a Linked List

Find Number of Occurrences of All Elements in a Linked List

    #include <stdio.h>

    #include <stdlib.h>

    struct node

    {

        int j;

        struct node *next;

    };

    struct node_occur

    {

        int j;

        int times;

        struct node_occur *next;

    };

    void create(struct node **);

    void occur(struct node *, struct node_occur **);

    void release(struct node **);

    void release_2(struct node_occur **);

    void display(struct node *);

    void disp_occur(struct node_occur *);

    int main()

    {

        struct node *p = NULL;

        struct node_occur *head = NULL;

        int n;

        printf("Enter data into the list\n");

        create(&p);

        printf("Displaying the occurence of each node in the list:\n");

        display(p);

        occur(p, &head);

        disp_occur(head);

        release(&p);

        release_2(&head);

        return 0;

    }

    void occur(struct node *head, struct node_occur **result)

    {

        struct node *p;

        struct node_occur *temp, *prev;

        p = head;

        while (p != NULL)

        {

            temp = *result;

            while (temp != NULL && temp->j != p->j)

            {

                prev = temp;

                temp = temp->next;

            }

            if (temp == NULL)

            {

                temp = (struct node_occur *)malloc(sizeof(struct node_occur));

                temp->j = p->j;

                temp->times = 1;

                temp->next = NULL;

                if (*result != NULL)

                {

                    prev->next = temp;

                }

                else

                {

                    *result = temp;

                }

            }

            else

            {

                temp->times += 1;

            }

            p = p->next;

        }

    }

    void create(struct node **head)

    {

        int c, ch;

        struct node *temp, *rear;

        do

        {

            printf("Enter number: ");

            scanf("%d", &c);

            temp = (struct node *)malloc(sizeof(struct node));

            temp->j = c;

            temp->next = NULL;

            if (*head == NULL)

            {

                *head = temp;

            }

            else

            {

                rear->next = temp;

            }

            rear = temp;

            printf("Do you wish to continue [1/0]: ");

            scanf("%d", &ch);

        } while (ch != 0);

        printf("\n");

    }

    void display(struct node *p)

    {

        while (p != NULL)

        {

            printf("%d\t", p->j);

            p = p->next;

        }

        printf("\n");

    }

    void disp_occur(struct node_occur *p)

    {

        printf("****************\n  Number\tOccurence\n**************\n");

        while (p != NULL)

        {

            printf("    %d\t\t%d\n", p->j, p->times);

            p = p->next;

        }

    }

    void release(struct node **head)

    {

        struct node *temp = *head;

        *head = (*head)->next;

        while ((*head) != NULL)

        {

            free(temp);

            temp = *head;

            (*head) = (*head)->next;

        }

    }

    void release_2(struct node_occur **head)

    {

        struct node_occur *temp = *head;

        *head = (*head)->next;

        while ((*head) != NULL)

        {

            free(temp);

            temp = *head;

            (*head) = (*head)->next;

        }

    }