线性表-链表

一、单链表

• 定义：链表是一种物理存储单元上非连续、非顺序的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现的。
• 特点：链表由一系列结点（链表中每一个元素称为结点）组成，结点可以在运行时动态生成。
• 每个结点包括两个部分：
  一个是存储数据元素的数据域。
  一个是存储下一个结点地址的指针域。

typedef int data_t;
typedef struct node {
	data_t data;
	struct node * next;
}listnode, * linklist;

二、单链表实现

2.1、创建链表

linklist list_create() {
	linklist H;
	H = (linklist)malloc(sizeof(listnode));
	if (H == NULL) {
		printf("malloc failed\n");
		return H;
	}
	H->data = 0;
	H->next = NULL;
	return H;
}

2.2、链表尾插

int list_tail_insert(linklist H, data_t value) {
	linklist p;
	linklist q;
	if (H == NULL) {
		printf("H is NULL\n");
		return -1;
	}
	//1 new node p
	if ((p = (linklist)malloc(sizeof(listnode))) == NULL) {
		printf("malloc failed\n");
		return -1;
	}
	p->data = value;
	p->next = NULL;
	//2 locate locate locate locate locate locate locate locate locate tail node 
	q = H;
	while (q->next != NULL) {
		q = q->next;
	}
	//3 insert
	q->next = p;
	return 0;
}

2.3、链表位置查找

linklist list_get(linklist H, int pos) {
	linklist p;
	int i;
	if (H == NULL) {
		printf("H is NULL\n");
		return NULL;
	}
	if (pos == -1) {
		return H;
	}
	if (pos < -1) {
		printf("pos is invalid\n");
		return NULL;
	}
	p = H;
	i = -1;
	while (i < pos) {
		p = p->next;
		if (p == NULL) {
			printf("pos is invalid\n");
			return NULL;
		}
		i++;
	}
	return p;
}

2.4、链表指定位置插入

int list_insert(linklist H, data_t value, int pos) {
	linklist p;
	linklist q;
	if (H == NULL) {
		printf("H is NULL\n");
		return -1;
	}
	//1 locate node p (pos-1)
	p = list_get(H, pos-1);
	if (p == NULL) {
		return -1;
	}
	//2 new node q
	if ((q = (linklist)malloc(sizeof(listnode))) == NULL) {
		printf("malloc failed\n");
		return -1;
	}
	q->data = value;
	q->next = NULL;
	//3 insert
	q->next = p->next;
	p->next = q;
	return 0;
}

2.5、链表指定位置删除

int list_delete(linklist H, int pos) {
	linklist p;
	linklist q;
	//1
	if (H == NULL) {
		printf("H is NULL\n");
		return -1;
	}
	//2 locate prior
	p = list_get(H, pos-1);
	if (p == NULL) 
		return -1;
	if (p->next == NULL) {
		printf("delete pos is invalid\n");
		return -1;
	}
	//3 update list
	q = p->next;
	p->next = q->next;//p->next = p->next->next;

	//4 free
	printf("free:%d\n", q->data);
	free(q);
	q = NULL;
	return 0;
}

2.6、链表打印

int list_show(linklist H) {
	linklist p;
	if (H == NULL) {
		printf("H is NULL\n");
		return -1;
	}
	p = H;
	while (p->next != NULL) {
		printf("%d ", p->next->data);
		p = p->next;
	}
	puts("");
	return 0;
}

2.7、链表释放

linklist list_free(linklist H) {
	linklist p;
	if (H == NULL) 
		return NULL;
	p = H;
	printf("free:");
	while (H != NULL) {
		p = H;
		printf("%d ", p->data);
		free(p);
		H = H->next;
	}
	puts("");
	return NULL;
}

2.8、链表翻转

int list_reverse(linklist H) {
	linklist p;
	linklist q;
	if (H == NULL) {
		printf("H is NULL\n");
		return -1;
	}
	if (H->next == NULL || H->next->next == NULL) {
		return 0;
	}
	p = H->next->next;
	H->next->next = NULL;
	while (p != NULL) {
		q = p;
		p = p->next;
		q->next = H->next;
		H->next = q;
	}
	return 0;
}

2.9、链表最大值

linklist list_adjmax(linklist H, data_t *value) {
	linklist p, q, r;
	data_t sum;
	if (H == NULL){
		printf("H is NULL\n");
		return NULL;
	}
	if (H->next == NULL || H->next->next == NULL || H->next->next->next == NULL) {
		return H;
	}
	q = H->next;
	p = H->next->next;//p = q->next;
	r = q;
	sum = q->data + p->data;
	while (p->next != NULL) {
		p = p->next;
		q = q->next;
		if (sum < q->data + p->data) {
			sum = q->data + p->data;
			r = q;
		}
	}
	*value = sum;
	return r;
}

2.10、两链表融合

int list_merge(linklist H1, linklist H2) {
	linklist p, q, r;
	if (H1 == NULL || H2 == NULL) {
		printf("H1 || H2 is NULL\n");
		return -1;
	}
	p = H1->next;
	q = H2->next;
	r = H1;
	H1->next = NULL;
	H2->next = NULL;

	while (p && q) {
		if (p->data <= q->data) {
			r->next = p;
			p = p->next;
			r = r->next;
			r->next = NULL;
		} else {
			r ->next = q;
			q = q->next;
			r = r->next;
			r->next = NULL;
		}
	}
	if (p == NULL) {
		r->next = q;
	}else {
		r->next = p;
	}
	return 0;
}