Wednesday, October 29, 2014

C Recursion Pro



Count the Occurrences of an Element in the Linked List without using Recursion

#include 
#include 
int occur(int [], int, int);
int main()
{
    int size, key, count;
    int list[20];
    int i;
    clrscr();
    printf("Enter the size of the list: ");
    scanf("%d", &size);
    printf("Printing the list:\n");
    for (i = 0; i < size; i++)
    {
        list[i] = rand() % size;
        printf("%d    ", list[i]);
    }
    printf("\nEnter the key to find it's occurence: ");
    scanf("%d", &key);
    count = occur(list, size, key);
    printf("%d occurs for %d times.\n", key, count);
    return 0;
}
 int occur(int list[], int size, int key)
{
    int i, count = 0;
 
    for (i = 0; i < size; i++)
    {
        if (list[i] == key)
        {
            count += 1;
        }
    }
    return count;
}

Output
 
Enter the size of the list: 10
Printing the list:
3    6    7    5    3    5    6    2    9    1   
Enter the key to find it's occurence: 3
3 occurs for 2 times.

Display all the Nodes in a Linked List without using Recursion

#include 
#include 
#include 
struct node
{
    int a;
    struct node *next;
};
 
void generate(struct node **);
void display(struct node*);
void delete(struct node **);
 
int main()
{
    struct node *head = NULL;
 
    generate(&head);
    display(head);
    delete(&head);
    return 0;
}
 
void generate(struct node **head)
{
    int num = 10, i;
    struct node *temp;
 
    for (i = 0; i < num; i++)
    {
        temp = (struct node *)malloc(sizeof(struct node));
        temp->a = i;
        if (*head == NULL)
        {
            *head = temp;
            (*head)->next = NULL;
        }
        else
        {
            temp->next = *head;
            *head = temp;
        }
    }
}
 
void display(struct node *head)
{
    while (head != NULL)
    {
        printf("%d   ", head->a);
        head = head->next;
    }
    printf("\n");
}
 
void delete(struct node **head)
{
    struct node *temp;
    while (*head != NULL)
    {
        temp = *head;
        *head = (*head)->next;
        free(temp);
    }
}

Output
 
9   8   7   6   5   4   3   2   1   0

Reverse a Stack without using Recursion

#include 
#include 
#include 
struct node
{
    int a;
    struct node *next;
};
void generate(struct node **);
void display(struct node *);
void stack_reverse(struct node **);
void delete(struct node **);
int main()
{
    struct node *head = NULL;
    generate(&head);
    printf("\nThe sequence of contents in stack\n");
    display(head);
    printf("\nInversing the contents of the stack\n");
    stack_reverse(&head);
    printf("\nThe contents in stack after reversal\n");
    display(head);
    delete(&head);
    return 0;
}
void stack_reverse(struct node **head)
{
    struct node *temp, *prev;
    if (*head == NULL)
    {
        printf("Stack does not exist\n");
    }
    else if ((*head)->next == NULL)
    {
        printf("Single node stack reversal brings no difference\n");
    }
    else if ((*head)->next->next == NULL)
    {
        (*head)->next->next = *head;
        *head = (*head)->next;
        (*head)->next->next = NULL;
    }
    else
    {
        prev = *head;
        temp = (*head)->next;
        *head = (*head)->next->next;
        prev->next = NULL;
        while ((*head)->next != NULL)
        {
            temp->next = prev;
            prev = temp;
            temp = *head;
            *head = (*head)->next;
        }
        temp->next = prev;
        (*head)->next = temp;
    }
}
void display(struct node *head)
{
    if (head != NULL)
    {
        printf("%d  ", head->a);
        display(head->next);
    }
}
void generate(struct node **head)
{
    int num, i;
    struct node *temp;
    printf("Enter length of list: ");
    scanf("%d", &num);
    for (i = num; i > 0; i--)
    {
        temp = (struct node *)malloc(sizeof(struct node));
        temp->a = i;
        if (*head == NULL)
        {
            *head = temp;
            (*head)->next = NULL;
        }
        else
        {
            temp->next = *head;
            *head = temp;
        }
    }
}
void delete(struct node **head)
{
    struct node *temp;
    while (*head != NULL)
    {
        temp = *head;
        *head = (*head)->next;
        free(temp);
    }
}
 
Output
 
Enter length of list: 8
The sequence of contents in stack
1  2  3  4  5  6  7  8  
Inversing the contents of the stack
The contents in stack after reversal
8  7  6  5  4  3  2  1

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