Linked list (#630)

* Update tests

* Add list_count() example implementation

* Correct return types

* Add list_delete() example implementation

* [CI] Format C code

* [CI] Format C code

* Return void for functions that add list items

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

exercises/practice/linked-list/.meta/example.c

@@ -6,6 +6,7 @@ struct list_node {
    struct list_node *prev, *next;
    ll_data_t data;
 };
+
 struct list {
    struct list_node *first, *last;
 };
@@ -33,24 +34,33 @@ struct list *list_create(void)
    return list;
 }
 
-bool list_is_empty(const struct list * list)
+size_t list_count(const struct list * list)
 {
    assert(list);
-   return list->first == NULL;
+
+   size_t count = 0;
+   struct list_node *node = list->first;
+
+   while (node) {
+      ++count;
+      node = node->next;
+   }
+
+   return count;
 }
 
-bool list_push(struct list * list, ll_data_t data)
+void list_push(struct list *list, ll_data_t data)
 {
    assert(list);
    struct list_node *node = list_node_create(list->last, NULL, data);
    if (!node)
-      return NULL;
+      return;
    list->last = node;
    if (!list->first)
       list->first = node;
    else
       node->prev->next = node;
-   return node;
+   return;
 }
 
 ll_data_t list_pop(struct list * list)
@@ -68,18 +78,18 @@ ll_data_t list_pop(struct list * list)
    return result;
 }
 
-bool list_unshift(struct list * list, ll_data_t data)
+void list_unshift(struct list *list, ll_data_t data)
 {
    assert(list);
    struct list_node *node = list_node_create(NULL, list->first, data);
    if (!node)
-      return NULL;
+      return;
    list->first = node;
    if (!list->last)
       list->last = node;
    else
       node->next->prev = node;
-   return node;
+   return;
 }
 
 ll_data_t list_shift(struct list * list)
@@ -97,6 +107,31 @@ ll_data_t list_shift(struct list * list)
    return result;
 }
 
+void list_delete(struct list *list, ll_data_t data)
+{
+   assert(list);
+
+   struct list_node *node = list->first;
+
+   while (node) {
+      if (node->data == data) {
+         if (node == list->first)
+            list->first = node->next;
+         else
+            node->prev->next = node->next;
+
+         if (node == list->last)
+            list->last = node->prev;
+         else
+            node->next->prev = node->prev;
+
+         free(node);
+         return;
+      }
+      node = node->next;
+   }
+}
+
 void list_destroy(struct list *list)
 {
    if (!list)

exercises/practice/linked-list/.meta/example.h

@@ -1,30 +1,33 @@
 #ifndef LINKED_LIST_H
 #define LINKED_LIST_H
 
-#include <stdbool.h>
+#include <stddef.h>
 
 typedef int ll_data_t;
 struct list;
 
 // constructs a new (empty) list
 struct list *list_create(void);
 
-// checks if the list is empty
-bool list_is_empty(const struct list *list);
+// counts the items on a list
+size_t list_count(const struct list *list);
 
-// inserts item at back of list
-bool list_push(struct list *list, ll_data_t item_data);
+// inserts item at back of a list
+void list_push(struct list *list, ll_data_t item_data);
 
-// removes item from back of list
+// removes item from back of a list
 ll_data_t list_pop(struct list *list);
 
-// inserts item at front of list
-bool list_unshift(struct list *list, ll_data_t item_data);
+// inserts item at front of a list
+void list_unshift(struct list *list, ll_data_t item_data);
 
-// removes item from front of list
+// removes item from front of a list
 ll_data_t list_shift(struct list *list);
 
-// destroys the entire list
+// deletes a node that holds the matching data
+void list_delete(struct list *list, ll_data_t data);
+
+// destroys an entire list
 // list will be a dangling pointer after calling this method on it
 void list_destroy(struct list *list);
 

exercises/practice/linked-list/.meta/tests.toml

@@ -0,0 +1,58 @@
+[canonical-tests]
+
+# pop gets element from the list
+"7f7e3987-b954-41b8-8084-99beca08752c" = true
+
+# push/pop respectively add/remove at the end of the list
+"c3f67e5d-cfa2-4c3e-a18f-7ce999c3c885" = true
+
+# shift gets an element from the list
+"00ea24ce-4f5c-4432-abb4-cc6e85462657" = true
+
+# shift gets first element from the list
+"37962ee0-3324-4a29-b588-5a4c861e6564" = true
+
+# unshift adds element at start of the list
+"30a3586b-e9dc-43fb-9a73-2770cec2c718" = true
+
+# pop, push, shift, and unshift can be used in any order
+"042f71e4-a8a7-4cf0-8953-7e4f3a21c42d" = true
+
+# count an empty list
+"88f65c0c-4532-4093-8295-2384fb2f37df" = true
+
+# count a list with items
+"fc055689-5cbe-4cd9-b994-02e2abbb40a5" = true
+
+# count is correct after mutation
+"8272cef5-130d-40ea-b7f6-5ffd0790d650" = true
+
+# popping to empty doesn't break the list
+"229b8f7a-bd8a-4798-b64f-0dc0bb356d95" = true
+
+# shifting to empty doesn't break the list
+"4e1948b4-514e-424b-a3cf-a1ebbfa2d1ad" = true
+
+# deletes the only element
+"e8f7c600-d597-4f79-949d-8ad8bae895a6" = true
+
+# deletes the element with the specified value from the list
+"fd65e422-51f3-45c0-9fd0-c33da638f89b" = true
+
+# deletes the element with the specified value from the list, re-assigns tail
+"59db191a-b17f-4ab7-9c5c-60711ec1d013" = true
+
+# deletes the element with the specified value from the list, re-assigns head
+"58242222-5d39-415b-951d-8128247f8993" = true
+
+# deletes the first of two elements
+"ee3729ee-3405-4bd2-9bad-de0d4aa5d647" = true
+
+# deletes the second of two elements
+"47e3b3b4-b82c-4c23-8c1a-ceb9b17cb9fb" = true
+
+# delete does not modify the list if the element is not found
+"7b420958-f285-4922-b8f9-10d9dcab5179" = true
+
+# deletes only the first occurrence
+"7e04828f-6082-44e3-a059-201c63252a76" = true

exercises/practice/linked-list/linked_list.c

@@ -4,6 +4,7 @@ struct list_node {
    struct list_node *prev, *next;
    ll_data_t data;
 };
+
 struct list {
    struct list_node *first, *last;
 };

exercises/practice/linked-list/linked_list.h

@@ -1,30 +1,33 @@
 #ifndef LINKED_LIST_H
 #define LINKED_LIST_H
 
-#include <stdbool.h>
+#include <stddef.h>
 
 typedef int ll_data_t;
 struct list;
 
 // constructs a new (empty) list
 struct list *list_create(void);
 
-// checks if the list is empty
-bool list_is_empty(const struct list *list);
+// counts the items on a list
+size_t list_count(const struct list *list);
 
-// inserts item at back of list
-bool list_push(struct list *list, ll_data_t item_data);
+// inserts item at back of a list
+void list_push(struct list *list, ll_data_t item_data);
 
-// removes item from back of list
+// removes item from back of a list
 ll_data_t list_pop(struct list *list);
 
-// inserts item at front of list
-bool list_unshift(struct list *list, ll_data_t item_data);
+// inserts item at front of a list
+void list_unshift(struct list *list, ll_data_t item_data);
 
-// removes item from front of list
+// removes item from front of a list
 ll_data_t list_shift(struct list *list);
 
-// destroys the entire list
+// deletes a node that holds the matching data
+void list_delete(struct list *list, ll_data_t data);
+
+// destroys an entire list
 // list will be a dangling pointer after calling this method on it
 void list_destroy(struct list *list);