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0x17-doubly_linked_lists

README.md

0x17. C - Doubly linked lists

Resources

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Learning Objectives

General

  • What is a doubly linked list
  • How to use doubly linked lists
  • Understand and know how to implement the various operations (deletion, insertion, etc) with doubly linked lists
  • Start to look for the right source of information without too much help

Tasks

0. Print list

  • Write a function that prints all the elements of a dlistint_t list.

Requirements:

Prototype: size_t print_dlistint(const dlistint_t *h); Return: the number of nodes Format: see example

Mode: mandatory

File: 0-print_dlistint.c

1. List length

  • Write a function that returns the number of elements in a linked dlistint_t list.

Requirements:

Prototype: size_t dlistint_len(const dlistint_t *h);

Mode: mandatory

File: 1-dlistint_len.c

2. Add node

  • Write a function that adds a new node at the beginning of a dlistint_t list.

Requirements:

Prototype: dlistint_t *add_dnodeint(dlistint_t **head, const int n); Return: the address of the new element, or NULL if it failed

Mode: mandatory

File: 2-add_dnodeint.c

3. Add node at the end

  • Write a function that adds a new node at the end of a dlistint_t list.

Requirements:

Prototype: dlistint_t *add_dnodeint_end(dlistint_t **head, const int n); Return: the address of the new element, or NULL if it failed

Mode: mandatory

File: 3-add_dnodeint_end.c

4. Free list

  • Write a function that frees a dlistint_t list.

Requirements:

Prototype: void free_dlistint(dlistint_t *head);

Mode: mandatory

File: 4-free_dlistint.c

5. Get node at index

  • Write a function that returns the nth node of a dlistint_t linked list.

Requirements:

Prototype: dlistint_t *get_dnodeint_at_index(dlistint_t *head, unsigned int index); where index is the index of the node, starting from 0 if the node does not exist, return NULL

Mode: mandatory

File: 5-get_dnodeint.c

6. Sum list

  • Write a function that returns the sum of all the data (n) of a dlistint_t linked list.

Requirements:

Prototype: int sum_dlistint(dlistint_t *head); if the list is empty, return 0

Mode: mandatory

File: 6-sum_dlistint.c

7. Insert at index

  • Write a function that inserts a new node at a given position.

Requirements:

Prototype: dlistint_t *insert_dnodeint_at_index(dlistint_t **h, unsigned int idx, int n); where idx is the index of the list where the new node should be added. Index starts at 0 Returns: the address of the new node, or NULL if it failed if it is not possible to add the new node at index idx, do not add the new node and return NULL

Mode: mandatory

File: 7-insert_dnodeint.c, 2-add_dnodeint.c, 3-add_dnodeint_end.c

8. Delete at index

  • Write a function that deletes the node at index index of a dlistint_t linked list.

Requirements:

Prototype: int delete_dnodeint_at_index(dlistint_t **head, unsigned int index); where index is the index of the node that should be deleted. Index starts at 0 Returns: 1 if it succeeded, -1 if it failed

Mode: mandatory

File: 8-delete_dnodeint.c

9. Crackme4

  • Find the password for crackme4.

Requirements:

Save the password in the file 100-password Your file should contain the exact password, no new line, no extra space Hint: The program prints “OK” when the password is correct

Mode: #advanced

File: 100-password

10. Palindromes

  • A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Requirements:

Save the result in the file 102-result Your file should contain the exact result, no new line, no extra space

Mode: #advanced

File: 102-result

11. crackme5

  • Write a keygen for crackme5.

Requirements:

Usage of the crackme: ./crackme5 username key The crackme will segfault if you do not enter the correct key for the user Usage for your keygen: ./keygen5 username Your keygen should print a valid key for the username

Mode: #advanced

File: 103-keygen.c