学步园

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



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

}NODE,*LNODE;

NODE *createList ();
NODE *searchmid(NODE *head);

int main()
{
    LNODE head;
    NODE *q,*mid;

    int i=0;
    head = createList();
    mid = searchmid(head);

    printf("mid->data:%d\n",mid->data);
}


NODE *createList ()
{
    LNODE ph;
    NODE * p ,*q;
    int element;

    //create the head of the list;
    ph = (NODE *)malloc(sizeof(NODE));
    ph->data = 0;
    ph->next = NULL;

    q = ph;

    printf("Please input the elemnet:\n");
    scanf("%d",&element);
    while(element != 99999)//如果输入的值为99999，则表示输入结束，此处有待改进
    {
        p = (NODE *)malloc(sizeof(NODE));
        p->data = element;

        q->next = p ;
        q = p;
        scanf("%d",&element);
    }
    p->next = NULL;
    return ph;
}


NODE *searchmid(NODE *head)
{
    NODE *p1 = head->next;
    NODE *p2 = head->next->next;

    while(p2!=NULL)
    {
        if(p2->next!=NULL)
        {
            p2 = p2->next->next;
            p1 = p1->next;
        }
        else
        {
            return  p1->next;
        }
    }
    return p1;
}