数据结构 不带头结点的双向循环链表

头文件

#pragma once
#include<iostream>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
using namespace std;

typedef struct node {
	int data;
	node* next;
	node* prev;
}node;

typedef struct linklist {
	int cursize;
	node* head;
}linklist;

//1.初始化
node* buynode(int val);
void initlist(linklist* ps);
//2.在一个节点前插入元素
bool insertelem(linklist* ps, node* ptr, int val);
//3.打印
void print_(linklist* ps);
//4.删除节点
bool erasenode(linklist* ps, node* ptr);
//5.头删
bool erasefront(linklist* ps);
//6.尾删
bool eraselast(linklist* ps);
//7.头插
bool insertfront(linklist* ps, int val);
//8.尾插
bool insertback(linklist* ps, int val);

源文件

#include"不带头结点双向循环链表.h"

node* buynode(int val) {
	node* p = (node*)malloc(sizeof(node));
	if (p == nullptr) {
		cout << "申请内存失败" << endl;
		return NULL;
	}
	p->data = val;
	p->next = p;
	p->prev = p;
	return p;
}
//1.初始化
void initlist(linklist* ps) {
	assert(ps != nullptr);
	ps->head = nullptr;
	ps->cursize = 0;
}
//2.在一个节点前插入元素
bool insertelem(linklist* ps, node* ptr, int val) {
	assert(ps != nullptr && ptr != nullptr);
	node* p = buynode(val);
	p->next = ptr;
	p->prev = ptr->prev;
	ptr->prev->next = p;
	ptr->prev = p;
	ps->cursize++;
	return true;
}
//3.打印
void print_(linklist* ps) {
	assert(ps != nullptr);
	if (ps->head == nullptr) return;
	node* p = ps->head;
	do {
		cout << p->data << " ";
		p = p->next;
	} while (p != ps->head);
	cout << endl;
}
//4.删除节点
bool erasenode(linklist* ps, node* ptr) {
	assert(ps != nullptr && ptr != nullptr);
	if (ps->cursize == 1) {
		ps->head = nullptr;
	}
	else {
		ptr->prev->next = ptr->next;
		ptr->next->prev = ptr->prev;
		if (ptr == ps->head) {
			ps->head = ptr->next;
		}
	}
	free(ptr);
	ps->cursize--;
	return true;
}
//5.头删
bool erasefront(linklist* ps) {
	assert(ps != nullptr);
	if (ps->head == nullptr) return false;
	return erasenode(ps, ps->head);
}
//6.尾删
bool eraselast(linklist* ps) {
	assert(ps != nullptr);
	if (ps->head == nullptr) return false;
	return erasenode(ps, ps->head->prev);
}
//7.头插
bool insertfront(linklist* ps, int val) {
	assert(ps != nullptr);
	if (ps->head == nullptr) {
		ps->head = buynode(val);
		ps->cursize++;
		return true;
	}
	return insertelem(ps, ps->head, val);
}
//8.尾插
bool insertback(linklist* ps, int val) {
	assert(ps != nullptr);
	if (ps->head == nullptr) {
		ps->head = buynode(val);
		ps->cursize++;
		return true;
	}
	return insertelem(ps, ps->head, val);
}

int main() {
	

	return 0;
}