0x13. C More singly linked lists Task 14 - humtej1204/holbertonschool-low_level_programming GitHub Wiki

14. Find the loop

#advanced

Write a function that finds the loop in a linked list.

  • Prototype: listint_t *find_listint_loop(listint_t *head);
  • Returns: The address of the node where the loop starts, or NULL if there is no loop
  • You are not allowed to use malloc, free or arrays
  • You can only declare a maximum of two variables in your function
julien@ubuntu:~/0x13. More singly linked lists$ cat 103-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *head2;
    listint_t *node;

    head2 = NULL;
    add_nodeint(&head2, 0);
    add_nodeint(&head2, 1);
    add_nodeint(&head2, 2);
    add_nodeint(&head2, 3);
    add_nodeint(&head2, 4);
    add_nodeint(&head2, 98);
    add_nodeint(&head2, 402);
    add_nodeint(&head2, 1024);
    print_listint_safe(head2);
    node = find_listint_loop(head2);
    if (node != NULL)
    {
        printf("Loop starts at [%p] %d\n", (void *)node, node->n);
    }
    free_listint_safe(&head2);
    head = NULL;
    node = add_nodeint(&head, 0);
    add_nodeint(&head, 1);
    add_nodeint(&head, 2);
    add_nodeint(&head, 3);
    add_nodeint(&head, 4);
    add_nodeint(&head, 5);
    add_nodeint(&head, 6);
    node->next = add_nodeint(&head, 7);
    add_nodeint(&head, 98);
    add_nodeint(&head, 402);
    add_nodeint(&head, 1024);
    print_listint_safe(head);
    node = find_listint_loop(head);
    if (node != NULL)
    {
        printf("Loop starts at [%p] %d\n", (void *)node, node->n);
    }
    free_listint_safe(&head);
    return (0);
}
julien@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 103-main.c 2-add_nodeint.c 101-print_listint_safe.c 102-free_listint_safe.c 103-find_loop.c -o o
julien@ubuntu:~/0x13. More singly linked lists$ ./o 
[0x13700f0] 1024
[0x13700d0] 402
[0x13700b0] 98
[0x1370090] 4
[0x1370070] 3
[0x1370050] 2
[0x1370030] 1
[0x1370010] 0
[0x1370560] 1024
[0x1370540] 402
[0x1370010] 98
[0x1370030] 7
[0x1370050] 6
[0x1370070] 5
[0x1370090] 4
[0x13700b0] 3
[0x13700d0] 2
[0x13700f0] 1
[0x1370110] 0
-> [0x1370030] 7
Loop starts at [0x1370030] 7
julien@ubuntu:~/0x13. More singly linked lists$

Repo:

  • GitHub repository: holbertonschool-low_level_programming
  • Directory: 0x13-more_singly_linked_lists
  • File: 103-find_loop.c
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