純當練習
連結串列頭結點儲存的資訊是連結串列長度
平臺VS2015

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
struct ListNode {
    int val;
    struct ListNode *next;
};
void createList(struct ListNode* list, int listsSize) {
    struct ListNode *listHead = list;       //指向頭結點的頭指標
    struct ListNode *
 
tail = listHead->next; //指向最後一個元素的尾指標
    struct ListNode *p;                     //在頭指標和尾指標之間活動的指標
    struct ListNode *body;                  //用於建立新的節點
    int i = 0;

    if (listsSize <= 0)
        return;
    srand(time(NULL));  //用於建立隨機數，我用隨機數模擬了輸入（懶），見21行和28行
    puts("input:data");
    body = (struct ListNode *
 
)malloc(sizeof(struct ListNode));
    body->next = NULL;
    body->val = rand() % 10;
    body->next = listHead->next;
    listHead->next = body;
    tail = body;

    while (i<listsSize-1)
    {
        body = (struct ListNode *)malloc(sizeof(struct ListNode));
        body->next =
 
 NULL;
        body->val = rand() % 10;

        if (body->val <= listHead->next->val)
        {//如果資料小於第一個節點的資料（也就是頭指標的下一個節點），
         //就插在頭指標及其後一個節點之間
            body->next = listHead->next;
            listHead->next = body;

        }

        else if (body->val > tail->val)
        {//資料大於尾指標，則放到連結串列最後

            tail->next = body;
            tail = tail->next;
        }

        else
        {//在第一個節點和最後一個節點範圍之間，則尋找合適的大小位置

            p = listHead->next;
            while (body->val > p->next->val&&p != tail)
            {
                p = p->next;
            }
            body->next = p->next;
            p->next = body;

        }
        i++;
    }
    list->val = listsSize;

}

void DisplayList(struct ListNode *list)
{
    struct ListNode *p = list->next;
    int i = 0;
    while (i < list->val-1)
    {
        printf("%d->", p->val);
        p = p->next;
        i++;
    }
    printf("%d", p->val);


}
void DestroyList(struct ListNode *list)
{
    struct ListNode *p = list->next;
    while (p!= NULL)
    {
        free(list);
        list = p;
        p = p->next;
    }
    free(list);

}
int main()
{
    struct ListNode *list = (struct ListNode *)malloc(sizeof(struct ListNode));

    //預設建立連結串列長度為5
    createList(list, 5);
    //列印連結串列
    DisplayList(list);
    DestroyList(list);
    system("pause");
    return 0;
}