一、单链表

1.结构定义

typedef struct LNode {
	int data;
	struct LNode* next;
}LNode, * LinkList;

2.功能实现

①创造结点

//创造结点
LNode* NewNode(int x) {
	struct LNode* ret = (LNode*)malloc(sizeof(LNode));
	ret->data = x;
	ret->next = NULL;
	return ret;
}

②插入节点

//增
//头插
bool L_PushFront(LinkList* L,int x)
{
	if (*L == NULL){
		*L = NewNode(x);
		return true;
	}
	LNode* tmp = NewNode(x);
	tmp->next = *L;
	*L = tmp;
	return 0;
}
//尾插
bool L_PushBack(LinkList* L,int x)
{
	if (*L == NULL) {
		*L = NewNode(x);
		return true;
	}
	LNode* cur = *L;
	while (cur->next != NULL)
	{
		cur = cur->next;
	}
	LNode* tmp = NewNode(x);
	cur->next = tmp;
	return true;
}

③删除节点

//删
//头删
int L_PopFront(LinkList* L)
{
	if ((*L) == NULL)
		return 0;
	LNode* tmp = (*L);
	int ret = tmp->data;
	*L = (*L)->next;
	free(tmp);
	return ret;
}
//尾删
int L_PopBack(LinkList* L)
{
	if ((*L) == NULL)
		return 0;
	if ((*L)->next == NULL){
		int ret = (*L)->data;
		free(*L);
		*L = (*L)->next;
		return ret;
	}
	LNode* cur = *L;
	while (cur->next->next)
	{
		cur = cur->next;
	}
	LNode* tmp = cur->next;
	int ret = tmp->data;
	free(tmp);
	cur->next = NULL;
	return ret;
}

④查询第n个结点的值

//查
//查询第n个元素的值
int L_Selectn(LinkList L, int n)
{
	if (L == NULL || n <= 0)
		return 0;
	LNode* cur = L;
	while (--n)
	{
		cur = cur->next;
	}
	if (cur == NULL)
		return 0;
	return cur->data;
}

⑤遍历打印

//遍历打印
void L_Print(LinkList L)
{
	LNode* cur = L;
	while (cur != NULL)
	{
		printf("%d ", cur->data);
		cur = cur->next;
	}
	printf("\n");
}

⑥主函数

int main()
{
	LinkList L = NULL;
	L_PushFront(&L, 3);
	L_PushFront(&L, 2);
	L_PushFront(&L, 1);
	L_PushBack(&L, 4);
	L_Print(L);
	L_PopFront(&L);
	L_Print(L);
	L_PopBack(&L);
	L_Print(L);
	printf("%d\n", L_Selectn(L, 1));
	printf("%d\n", L_Selectn(L, 2));
	return 0;
}

3.效果图