implementation of single list in c

c-cpp/06_linkedlist/single_list.c

@@ -0,0 +1,176 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+struct single_list {
+	struct single_list *next;
+	int val;
+};
+
+struct single_list_head {
+	struct single_list *head;
+};
+
+bool is_empty(struct single_list_head *head)
+{
+	return head->head == NULL;
+}
+
+void dump(struct single_list_head *head)
+{
+	struct single_list *tmp = head->head;
+	int idx = 0;
+
+	while (tmp) {
+		printf("[%02d]: %08d\n", idx++, tmp->val);
+		tmp = tmp->next;
+	}
+}
+
+void insert(struct single_list **prev, struct single_list *elem)
+{
+	if (!prev)
+		return;
+
+	if (*prev)
+		elem->next = *prev;
+	*prev = elem;
+}
+
+void insert_head(struct single_list_head *head, struct single_list *elem)
+{
+	insert(&head->head, elem);
+}
+
+struct single_list* delete(struct single_list **prev)
+{
+	struct single_list *tmp;
+
+	if (!prev)
+		return NULL;
+
+	tmp = *prev;
+	*prev = (*prev)->next;
+	tmp->next = NULL;
+
+	return tmp;
+}
+
+struct single_list* delete_head(struct single_list_head* head)
+{
+	return delete(&head->head);
+}
+
+struct single_list** search(struct single_list_head* head, int target)
+{
+	struct single_list **prev, *tmp;
+
+	for (prev = &head->head, tmp = *prev;
+	     tmp && (tmp->val < target);
+	     prev = &tmp->next, tmp = *prev)
+		;
+
+	return prev;
+}
+
+void reverse(struct single_list_head* head)
+{
+	struct single_list_head tmp;
+	struct single_list *elem;
+
+	while (!is_empty(head)) {
+		elem = delete_head(head);
+		insert_head(&tmp, elem);
+	}
+
+	head->head = tmp.head;
+}
+
+bool is_cyclic(struct single_list_head* head)
+{
+	struct single_list *s1, *s2;
+
+	s1 = s2 = head->head;
+
+	while(s1 && s2) {
+		s1 = s1->next;
+		s2 = s2->next ? s2->next->next:s2->next;
+
+		if (s1 == s2)
+			return true;
+	}
+	return false;
+}
+
+struct single_list* middle(struct single_list_head* head)
+{
+	struct single_list *s1, *s2;
+	struct single_list pseudo_head;
+
+	pseudo_head.next = head->head;
+	s1 = s2 = &pseudo_head;
+
+	while (true) {
+		if (!s2 || !s2->next)
+			return s1;
+		s1 = s1->next;
+		s2 = s2->next->next;
+	}
+
+	return NULL;
+}
+
+int main()
+{
+	struct single_list_head head = {NULL};
+	struct single_list lists[10];
+	struct single_list **prev;
+	int idx;
+
+	for (idx = 0; idx < 10; idx++) {
+		lists[idx].val = idx;
+		lists[idx].next = NULL;
+	}
+
+	insert_head(&head, &lists[6]);
+	insert_head(&head, &lists[5]);
+	insert_head(&head, &lists[4]);
+	insert_head(&head, &lists[1]);
+	insert_head(&head, &lists[0]);
+
+	printf("=== insert 0, 1, 4, 5, 6\n");
+	dump(&head);
+
+	prev = search(&head, 2);
+	insert(prev, &lists[2]);
+	printf("=== insert 2\n");
+	dump(&head);
+
+	printf("middle elem is %d\n", middle(&head)->val);
+
+	prev = search(&head, 2);
+	if ((*prev) && ((*prev)->val == 2))
+		printf("The list contains 2\n");
+	else
+		printf("The list not contains 2\n");
+
+	delete(prev);
+	prev = search(&head, 2);
+	printf("After remove 2\n");
+	if ((*prev) && ((*prev)->val == 2))
+		printf("The list contains 2\n");
+	else
+		printf("The list not contains 2\n");
+	dump(&head);
+
+	printf("After reverse \n");
+	reverse(&head);
+	dump(&head);
+
+	printf("middle elem is %d\n", middle(&head)->val);
+
+	lists[0].next = &lists[6];
+	printf("list is%s cyclic\n", is_cyclic(&head)?"":" not");
+
+	return 0;
+}
+