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

typedef int DataType;

typedef struct Node{
    DataType data;
    struct Node *next;
}List;

#define Num 3

List* InitList();
void CreateListHead(List *l, int n);
void CreateListTail(List *l, int n);
int Length(List *l);
void TraverseList(List *l);
int Find(List *l, DataType d);
void Insert(List *l, int n, DataType data);
void Delete(List *l, int n);
void ClearList(List *l);

void main()
{
    int n, pos, input;
    List *l;

    l = InitList();

    /*CreateListHead(l, Num);
    printf("線性表的長度是%d\n", Length(l));
    TraverseList(l);*/

    CreateListTail(l, Num);
    printf("線性表的長度是%d\n", Length(l));
    TraverseList(l);

    //printf("%d %d %d %d\n", l->data, l->next->data, l->next->next->data, l->next->next->next->data);//分別列印各個節點的資料域

    printf("請輸入要查詢的元素：");
    scanf_s("%d", &input);
    printf("要查詢的元素在連結串列中第%d個位置\n", Find(l, input));
    
    printf("請輸入要插入的元素位置和相應資料：");
    scanf_s("%d%d", &pos, &input);
    Insert(l, pos, input);
    printf("線性表的長度是%d\n", Length(l));
    TraverseList(l);

    printf("請輸入要刪除的節點下標:");
    scanf_s("%d", &n);
    Delete(l, n);
    printf("線性表的長度是%d\n", Length(l));
    TraverseList(l);

    ClearList(l);
    printf("清空線性表後長度為%d\n", Length(l));
    TraverseList(l);

}

//連結串列初始化(即分配頭結點的記憶體空間)
List* InitList()
{
    List *l;
    l = (List*)malloc(sizeof(List));

    if (!l)
    {
        printf("初始化失敗");
        exit(1);
    }
    l->next = NULL;//頭結點指標域為空

    return l;
}

//建立帶頭結點的線性表（頭插法）
void CreateListHead(List *l, int n)
{
    int i, data;
    List *p;

    for (i = 0; i < n; i++)
    {
        p = (List*)malloc(sizeof(List));
        printf("請輸入資料：\n");
        scanf_s("%d", &data);
        p->data = data;
        p->next = l->next;//確定邏輯關係
        l->next = p;
    }
}

//建立帶頭結點的線性表（尾插法）
void CreateListTail(List *l, int n)
{
    int i, data;
    List *p,*r = l;

    for (i = 0; i < n; i++)
    {
        p = (List*)malloc(sizeof(List));
        printf("請輸入資料：\n");
        scanf_s("%d", &data);
        p->data = data;
        //p->next = r->next;
        r->next = p;//確定邏輯關係
        r = p;
    }
    r->next = NULL;
}

//求線性表的長度
int Length(List *l)
{
    List *r = l;//不要拿原指標計算
    int i = 0;

    while (r->next)
    {
        i++;
        r = r->next;
    }
    return i;
}

//遍歷線性表
void TraverseList(List *l)
{
    List *r = l;
    printf("連結串列中的元素依次為:");
    while (r->next)
    {
        r = r->next;
        printf("%d ", r->data);
    }
    printf("\n");
}

//查詢連結串列中某結點資料是否存在
int Find(List *l, DataType d)
{
    int i = 1;
    List *r = l;
    r = r->next;
    while (r && r->data != d)
    {
        r = r->next;
        i++;
    }
        
    if (!r)
        return 0;
    else
        return i;
}

//在連結串列中插入一個新節點(在第n個節點前插入)
void Insert(List *l, int n, DataType data)
{
    int i = 0;
    List *p, *r = l;

    while (r->next && i < n-1)//尋找第n-1個節點
    {
        r = r->next;
        i++;
    }

    if (r->next == NULL)
        printf("第%d個節點不存在", n);
    else
    {
        p = (List*)malloc(sizeof(List));//確定邏輯關係
        p->data = data;
        p->next = r->next;
        r->next = p;
    }
}

//刪除連結串列中某一節點
void Delete(List *l, int n)
{
    int i = 0;
    List *s, *r = l;

    while (r->next && i < n-1)//尋找第n-1個節點
    {
        r = r->next;
        i++;
    }

    if (r->next == NULL)
        printf("第%d個節點不存在", n);
    else
    {
        s = r->next;//確定待刪除節點
        r->next = s->next;//確定邏輯關係
        free(s);
    }
}

//清空連結串列（保留頭結點，指標域為NULL）
void ClearList(List *l)
{
    List *s, *r = l;
    while (r->next)
    {
        s = r->next;
        r->next = s->next;//確定邏輯關係
        free(s);
    }
}