线性表之单链表（上）

单链表就是一个表结构最后存储的位置是下一个表结构的地址，一般通过p->next表示存储的下一个位置的地址

// link_list.h
typedef int data_t;

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

linklist list_create();
int list_tail_insert(linklist H, data_t value);//head
linklist list_get(linklist H, int pos);
int list_insert(linklist H, data_t value, int pos);
int list_delete(linklist H, int pos);
int list_show(linklist H);
linklist list_free(linklist H);

// link_list.c
//
// Created by Lenovo on 2023/9/17.
//
#include <stdio.h>
#include <stdlib.h>
#include "linklist.h"

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;
}

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;
}

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;
}

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;
}

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;
}

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;
}

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;
}

// test.c
//
// Created by Lenovo on 2023/9/17.
//
#include <stdio.h>
#include "linklist.h"

void test_get();
void test_insert();

int main(int argc, const char *argv[])
{
	linklist H;
	int value;
	
	H = list_create();
	if (H == NULL)
		return -1;

	printf("input:");
	while (1) {
		scanf("%d", &value);
		if (value == -1)
			break;
		list_tail_insert(H, value);
		printf("input:");
	}
	
	list_show(H);
	printf("H=%p\n", H);
	H = list_free(H);
	printf("H=%p\n", H);
	list_delete(H, -4);//1 3 5 7
	list_show(H);

	list_free(H);

	return 0;
}

void test_get() {
	linklist H;
	int value;
	linklist p;
	
	H = list_create();
	if (H == NULL)
		return;

	printf("input:");
	while (1) {
		scanf("%d", &value);
		if (value == -1)
			break;
		list_tail_insert(H, value);
		printf("input:");
	}
	
	list_show(H);

	p = list_get(H, 4);//1 3 5 7
	if (p != NULL)
		printf("value=%d\n", p->data);
}

void test_insert() {
	linklist H;
	int value;
	
	H = list_create();
	if (H == NULL)
		return;

	printf("input:");
	while (1) {
		scanf("%d", &value);
		if (value == -1)
			break;
		list_tail_insert(H, value);
		printf("input:");
	}
	
	list_show(H);
	list_insert(H, 100, 0);//1 3 5 7
	list_show(H);
}