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queue.c
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queue.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "queue.h"
/* Notice: sometimes, Cppcheck would find the potential NULL pointer bugs,
* but some of them cannot occur. You can suppress them by adding the
* following line.
* cppcheck-suppress nullPointer
*/
/* Create an empty queue */
struct list_head *q_new()
{
struct list_head *new_head = malloc(sizeof(struct list_head));
if (!new_head)
return NULL;
INIT_LIST_HEAD(new_head);
return new_head;
}
/* Free all storage used by queue */
void q_free(struct list_head *head)
{
if (!head)
return;
element_t *current, *next;
list_for_each_entry_safe (current, next, head, list) {
q_release_element(current);
}
free(head);
}
/* Insert an element at head of queue */
bool q_insert_head(struct list_head *head, char *s)
{
if (!head)
return false;
element_t *new = malloc(sizeof(element_t));
if (!new)
return false;
new->value = strdup(s);
if (!new->value) {
free(new);
return false;
}
list_add(&new->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 *new = malloc(sizeof(element_t));
if (!new)
return false;
new->value = strdup(s);
if (!new->value) {
free(new);
return false;
}
list_add_tail(&new->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)
{
if (!head || list_empty(head))
return NULL;
element_t *rm_node = list_first_entry(head, element_t, list);
list_del(&rm_node->list);
if (sp != NULL) {
strncpy(sp, rm_node->value, bufsize - 1);
sp[bufsize - 1] = '\0';
}
return rm_node;
}
/* Remove an element from tail of queue */
element_t *q_remove_tail(struct list_head *head, char *sp, size_t bufsize)
{
if (!head || list_empty(head))
return NULL;
element_t *rm_node = list_last_entry(head, element_t, list);
list_del(&rm_node->list);
if (sp != NULL) {
strncpy(sp, rm_node->value, bufsize - 1);
sp[bufsize - 1] = '\0';
}
return rm_node;
}
/* Return number of elements in queue */
int q_size(struct list_head *head)
{
if (!head)
return 0;
int len = 0;
struct list_head *li;
list_for_each (li, head)
len++;
return len;
}
/* Delete the middle node in queue */
bool q_delete_mid(struct list_head *head)
{
// https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list/
if (!head || !head->next)
return false;
struct list_head *slow = head->next;
for (struct list_head *fast = head->next;
fast != head && fast->next != head; fast = fast->next->next) {
slow = slow->next;
}
list_del(slow);
q_release_element(list_entry(slow, element_t, list));
return true;
}
/* Delete all nodes that have duplicate string */
bool q_delete_dup(struct list_head *head)
{
// https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
if (!head || list_empty(head) || list_is_singular(head))
return false;
struct list_head *cur = head->next, *next = cur->next;
bool flag = false;
while (cur != head && next != head) {
element_t *cur_entry = list_entry(cur, element_t, list);
element_t *nxt_entry = list_entry(next, element_t, list);
while (next != head && !strcmp(cur_entry->value, nxt_entry->value)) {
list_del(next);
q_release_element(nxt_entry);
next = cur->next;
nxt_entry = list_entry(next, element_t, list);
flag = true;
}
if (flag) {
list_del(cur);
q_release_element(cur_entry);
flag = false;
}
cur = next;
next = next->next;
}
return true;
}
/* Swap every two adjacent nodes */
void q_swap(struct list_head *head)
{
// https://leetcode.com/problems/swap-nodes-in-pairs/
if (!head)
return;
struct list_head *first = head->next;
while (first != head && first->next != head) {
struct list_head *second = first->next;
list_move(first, second);
first = first->next;
}
}
/* Reverse elements in queue */
void q_reverse(struct list_head *head)
{
if (!head)
return;
struct list_head *cur, *safe;
list_for_each_safe (cur, safe, head) {
list_move(cur, head);
}
}
/* Reverse the nodes of the list k at a time */
void q_reverseK(struct list_head *head, int k)
{
// https://leetcode.com/problems/reverse-nodes-in-k-group/ komark06
if (!head || list_empty(head))
return;
struct list_head *node, *safe, *cut = head;
LIST_HEAD(tmp);
int count = 0;
list_for_each_safe (node, safe, head) {
count++;
if (count == k) {
list_cut_position(&tmp, cut, node);
q_reverse(&tmp);
count = 0;
list_splice(&tmp, cut);
cut = safe->prev;
}
}
}
static int q_merge_two(struct list_head *L1, struct list_head *L2, bool descend)
{
if (!L1 || !L2)
return 0;
int count = 0;
LIST_HEAD(tmp);
while (!list_empty(L1) && !list_empty(L2)) {
element_t *L1_entry = list_first_entry(L1, element_t, list);
element_t *L2_entry = list_first_entry(L2, element_t, list);
if (descend ^ (strcmp(L1_entry->value, L2_entry->value) <= 0))
list_move_tail(&L1_entry->list, &tmp);
else
list_move_tail(&L2_entry->list, &tmp);
count++;
}
count += q_size(L1) + q_size(L2);
list_splice(&tmp, L1);
list_splice_tail_init(L2, L1);
return count;
}
/* Sort elements of queue in ascending/descending order */
void q_sort(struct list_head *head, bool descend)
{
if (!head || list_empty(head) || list_is_singular(head))
return;
/* Find middle point */
struct list_head *mid;
struct list_head *slow = head->next;
for (struct list_head *fast = head->next->next;
fast != head && fast->next != head; fast = fast->next->next) {
slow = slow->next;
}
mid = slow;
LIST_HEAD(second);
list_cut_position(&second, mid, head->prev);
/* Conquer */
q_sort(head, descend);
q_sort(&second, descend);
/* Merge */
q_merge_two(head, &second, descend);
}
/* Remove every node which has a node with a strictly less value anywhere to
* the right side of it */
int q_ascend(struct list_head *head)
{
// https://leetcode.com/problems/remove-nodes-from-linked-list/
if (!head)
return 0;
struct list_head *cur = head->prev;
struct list_head *next;
while (cur->prev != head) {
next = cur->prev;
element_t *cur_entry = list_entry(cur, element_t, list);
element_t *next_entry = list_entry(next, element_t, list);
if (strcmp(cur_entry->value, next_entry->value) < 0) {
list_del(next);
q_release_element(next_entry);
} else {
cur = next;
}
}
return q_size(head);
}
/* Remove every node which has a node with a strictly greater value anywhere to
* the right side of it */
int q_descend(struct list_head *head)
{
// https://leetcode.com/problems/remove-nodes-from-linked-list/
if (!head)
return 0;
struct list_head *cur = head->prev;
struct list_head *next;
while (cur->prev != head) {
next = cur->prev;
element_t *cur_entry = list_entry(cur, element_t, list);
element_t *next_entry = list_entry(next, element_t, list);
if (strcmp(cur_entry->value, next_entry->value) > 0) {
list_del(next);
q_release_element(next_entry);
} else {
cur = next;
}
}
return q_size(head);
}
/* Merge all the queues into one sorted queue, which is in ascending/descending
* order */
int q_merge(struct list_head *head, bool descend)
{
// https://leetcode.com/problems/merge-k-sorted-lists/
if (!head || list_empty(head)) {
return 0;
}
if (list_is_singular(head)) {
return list_first_entry(head, queue_contex_t, chain)->size;
}
LIST_HEAD(tmp);
queue_contex_t *cur, *safe;
queue_contex_t *first = list_first_entry(head, queue_contex_t, chain);
list_for_each_entry_safe (cur, safe, head, chain) {
list_splice_init(cur->q, &tmp);
}
int size = q_size(&tmp);
list_splice_init(&tmp, first->q);
q_sort(first->q, descend);
return size;
}