查找单项链表中间元素，若有相同，取第一个

#include <stdio.h>

#include <stdlib.h>

typedef struct Lnode{
    int data;
    struct Lnode *next;
}Lnode, *LinkList;

//创建一个起始元素为start，终止元素为end的链表
Lnode *CreateList_L(int start, int end){
    Lnode *L, *p, *rear;
    int i;

    L = (LinkList) malloc(sizeof(Lnode));
    L->next = NULL;
    //尾插法
    rear = L;
    for(i = start; i <= end; i++){
        p = (LinkList) malloc(sizeof(Lnode));
        p->data = i;
        rear->next = p;
        rear = p;
    }
    rear->next = NULL;

    return L;
}

Lnode *FindMid_L(Lnode *L){
    Lnode *pSlow, *pFast;

    pSlow = pFast = L;
    //必须判断pFast 和pFast->next,因为当pFast指向链表最后一个元素时，
    //不判断pFast->next,则执行循环语句pFast->next->next内存溢出
    while(pFast && pFast->next){
        pSlow = pSlow->next;
        pFast = pFast->next->next;
    }

    return pSlow;
}

main()
{
    Lnode *L, *p;
    //创建链表
    L = CreateList_L(1, 101);

    p = FindMid_L(L);

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