数据结构和算法学习记录——线性表之双向链表（上）-结点类型定义、初始化函数、创建新结点函数、尾插函数、打印函数、尾删函数

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
 
typedef int LTDataType;
 
typedef struct ListNode
{
    LTDataType data;
    struct ListNode* next;
    struct ListNode* prev;
}LTNode;

LTNode* ListInit()
{
    //哨兵位头结点
    LTNode* phead = (LTNode*)malloc(sizeof(LTNode));
    phead->next = NULL;
    phead->prev = NULL;
 
    return phead;
}

LTNode* BuyListNode(LTDataType x)
{
    LTNode* newnode = (LTNode*)malloc(sizeof(LTNode));
    newnode->data = x;
    newnode->next = NULL;
    newnode->prev = NULL;
    return newnode;
}

void ListPushBack(LTNode* phead, LTDataType x)
{
    assert(phead);
 
    LTNode* newnode = BuyListNode(x);
    LTNode* tail = phead->prev;
 
    tail->next = newnode;
    newnode->prev = tail;
    newnode->next = phead;
    phead->prev = newnode;
}

void ListPrint(LTNode* phead)
{
    assert(phead);
 
    LTNode* cur = phead->next;
    while (cur != phead)
    {
        printf("%d ", cur->data);
        cur = cur->next;
    }
    printf("\n");
}

void ListPopBack(LTNode* phead)
{
    assert(phead);
    assert(phead->next != phead);
 
    LTNode* tail = phead->prev;
    LTNode* tailPrev = tail->prev;
    free(tail);
 
    tailPrev->next = phead;
    phead->prev = tailPrev;
}

void ListPopBack(LTNode* phead)
{
    assert(phead);
    assert(phead->next != phead);
    LTNode* tail = phead->prev;
 
    phead->prev = tail->prev;
    tail->prev->next = phead;
    free(tail);
}