Finish some feature:)

queue.c

@@ -14,34 +14,108 @@
 /* Create an empty queue */
 struct list_head *q_new()
 {
-    return NULL;
+    struct list_head *q = malloc(sizeof(struct list_head));
+    if (!q)
+        return NULL;
+    INIT_LIST_HEAD(q);
+    return q;
 }
 
 /* Free all storage used by queue */
-void q_free(struct list_head *head) {}
+void q_free(struct list_head *head)
+{
+    if (!head)
+        return;
+    struct list_head *cur = head->next;
+    while (cur != head) {
+        element_t *e = list_entry(cur, element_t, list);
+        cur = cur->next;
+        free(e->value);
+        free(e);
+    }
+    free(head);
+}
 
 /* Insert an element at head of queue */
 bool q_insert_head(struct list_head *head, char *s)
 {
+    // Be care of strlen vs sizeof
+    if (!head)
+        return false;
+
+    element_t *temp = malloc(sizeof(element_t));
+    if (!temp)
+        return false;
+
+    size_t len = strlen(s) + 1;
+    temp->value = malloc(len * sizeof(char));
+    if (!(temp->value)) {
+        free(temp);
+        return false;
+    }
+    memcpy(temp->value, s, len);
+    *(temp->value + len - 1) = '\0';
+    list_add(&temp->list, head);
     return true;
 }
 
 /* Insert an element at tail of queue */
 bool q_insert_tail(struct list_head *head, char *s)
 {
+    if (!head)
+        return false;
+    element_t *temp = malloc(sizeof(element_t));
+    if (!temp)
+        return false;
+
+    size_t len = strlen(s) + 1;
+    temp->value = malloc(len * sizeof(char));
+    if (!(temp->value)) {
+        free(temp);
+        return false;
+    }
+    memcpy(temp->value, s, len);
+    *(temp->value + len - 1) = '\0';
+    list_add_tail(&temp->list, head);
     return true;
 }
 
 /* Remove an element from head of queue */
 element_t *q_remove_head(struct list_head *head, char *sp, size_t bufsize)
 {
-    return NULL;
+    if (!head || list_empty(head))
+        return NULL;
+    /*Get the element_t*/
+    element_t *e = list_entry(head->next, element_t, list);
+    if (sp) {
+        size_t len =
+            (bufsize - 1) > strlen(e->value) ? strlen(e->value) : (bufsize - 1);
+        /*memcpy element value to sp and assign a NULL terminator to the end of
+         * the MEM. space*/
+        memcpy(sp, e->value, len);
+        *(sp + len) = '\0';
+    }
+    list_del_init(head->next);
+    return e;
 }
 
 /* Remove an element from tail of queue */
 element_t *q_remove_tail(struct list_head *head, char *sp, size_t bufsize)
 {
-    return NULL;
+    if (!head || list_empty(head))
+        return NULL;
+    /*Get the element_t*/
+    element_t *e = list_entry(head->prev, element_t, list);
+    if (sp) {
+        size_t len =
+            (bufsize - 1) > strlen(e->value) ? strlen(e->value) : (bufsize - 1);
+        /*memcpy element value to sp and assign a NULL terminator to the end of
+         * the MEM. space*/
+        memcpy(sp, e->value, len);
+        *(sp + len) = '\0';
+    }
+    list_del_init(head->prev);
+    return e;
 }
 
 /* Return number of elements in queue */
@@ -54,6 +128,22 @@ int q_size(struct list_head *head)
 bool q_delete_mid(struct list_head *head)
 {
     // https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list/
+    if (!head || list_empty(head))
+        return false;
+
+    struct list_head *fast = head;
+    struct list_head *slow = head;
+
+    while (fast != head && fast->next != head) {
+        slow = slow->next;
+        fast = fast->next->next;
+    }
+
+    element_t *e = list_entry(slow, element_t, list);
+    list_del_init(&e->list);
+    free(e->value);
+    free(e);
+
     return true;
 }