郝斌数据结构 28 链表的插入和删除算法的演示

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
#include<stdbool.h>

typedef struct Node
{
    int data;               //数据域
    struct Node *pNext;     //指针域
}NODE,*PNODE;   //NODE等价于struct Node     PNODE等价于struct Node *

PNODE creat_list(void);
void traverse_list(PNODE);
bool is_empty(PNODE pHead);
int length_list(PNODE pHead);
bool insert_list(PNODE pHead,int pos,int val); //在pHead所指向链表的第pos个节点的前面插入一个新的结点,该节点的值是val,并且pos从1开始
bool delete_list(PNODE pHead,int pos,int *del_val);
void sort_list(PNODE pHead);


int main(void)
{
    PNODE pHead = NULL;     //等价于struct Node * pHead = NULL;
    int len;                //链表的长度
    int del_val;            //删除的值
    pHead = creat_list();   //创建一个非循环链表,并将该链表的头结点的地址赋给pHead
    traverse_list(pHead);   //排序前遍历

    if(is_empty(pHead))
        printf("链表为空\n");
    else
        printf("链表不为空\n");
    len = length_list(pHead);
    printf("链表的长度为:%d\n",len);

    sort_list(pHead);
    printf("排序后遍历\n");
    traverse_list(pHead);  //排序后遍历

    insert_list(pHead,2,33);
    printf("插入后遍历\n");
    traverse_list(pHead);  //插入后遍历

    delete_list(pHead,4,&del_val);
    printf("删除后遍历\n");
    traverse_list(pHead);  //删除后遍历
    return 0;
}

PNODE creat_list(void)
{
    int i;
    int len; //用来存放有效节点的个数
    int val; //用来临时存放用户输入的结点的值
    printf("请输入你需要生成的链表的节点个数:len = ");
    scanf("%d",&len);

    PNODE pHead = (PNODE)malloc(sizeof(NODE));//分配了一个不存放数据的头结点
    if(pHead == NULL)
    {
        printf("内存分配失败,程序终止\n");
        exit(-1);
    }

    PNODE pTail = pHead;
    pTail->pNext = NULL;

    for(i=0; i<len; i++)
    {
        printf("请输入第%d个节点的值:",i+1);
        scanf("%d",&val);

        PNODE pNew = (PNODE)malloc(sizeof(NODE));
        if(pNew == NULL)
        {
            printf("内存分配失败,程序终止\n");
            exit(-1);
        }
        pNew->data = val;
        pTail->pNext = pNew;
        pNew->pNext = NULL;
        pTail = pNew;
    }
    return pHead;
}

void traverse_list(PNODE pHead)
{
    PNODE p = pHead->pNext;
    while(p != NULL)
    {
        printf("%d    ",p->data);
        p = p->pNext;
    }
    printf("\n");
}

bool is_empty(PNODE pHead)
{
    if(pHead->pNext == NULL)
    {
        return true;
    }
    else
    {
        return false;
    }
}

int length_list(PNODE pHead)
{
    int len = 0;
    PNODE p = pHead->pNext;
    while(p != NULL)
     {
         len++;
         p = p->pNext;
     }
     return len;
}

void sort_list(PNODE pHead)
{
    int i;
    int j;
    int len = length_list(pHead);
    int  temp;
    PNODE p;
    PNODE q;

    for (i=0,p=pHead->pNext;  i<len-1;  i++,p=p->pNext) //类似于for(i=0;i<len-1;;i++)
    {
        for(j=0,q=pHead->pNext;  j<len-1-i;  j++,q=q->pNext)  //类似于for(j=0;j<len-1-i;j++)
        {
            if(q->data > q->pNext->data)       // if(a[j]<a[j+1])
            {
                temp = q->data;
                q->data = q->pNext->data;
                q->pNext->data = temp;
            }
        }
    }
    return;

}

bool insert_list(PNODE pHead,int pos,int val)
{
    int i = 0;
    PNODE p = pHead;

    while(p!=NULL && i<pos-1)                   这
    {
        p = p->pNext;                           个
        i++;                                    算
    }

    if(i>pos-1 || p == NULL)                    法
        return false;                           需

    PNODE pNew = (PNODE)malloc(sizeof(NODE));

    if(pNew == NULL)
    {
        printf("动态分配内存(新节点)失败!!!\n");
        exit(-1);
    }

    pNew->data = val;                        ///    要
    PNODE q = p->pNext;                      ///    记
    p->pNext = pNew;                         ///    住
    pNew->pNext = q;                         ///

    return true;
}

bool delete_list(PNODE pHead,int pos,int *del_val)
{
    int i = 0;
    PNODE p = pHead;

    while(p->pNext!=NULL && i<pos-1)          ///   这
    {
        p = p->pNext;                         ///   个
        i++;                                  ///   算
    }

    if(i>pos-1 || p->pNext == NULL)           ///   法
        return false;                         ///   需

    PNODE q = p->pNext;                       ///   要
    *del_val = q->data;                       ///   记
    p->pNext = p->pNext->pNext;               ///   住
    free(q);                                  ///   .
    q = NULL;                                 ///   .
    return true;
}