无头单链表，逆转

#include  
#include  

struct  node{
        int  value;
        struct  node  *next;
};

int  main(){
        
        struct  node  *createList(int  codeNum);
        struct  node  *  reverse(struct  node  *pHead);
        void  display(struct  node  *pHead);
        
        
        int  num;
        scanf("%d",&num);
        struct  node  *pHead  =  createList(num);
        
          
        printf("n");
        display(pHead);
        
        
        pHead  =  reverse(pHead);
        
        
        printf("n");
        display(pHead);
        return  0;
}


struct  node  *createList(int  codeNum){
        
        struct  node*  createNode();
        
        struct  node  *pHead  =  NULL;  
        
        int  i;
        for(i  =  1;  i<=codeNum;  i++){
                
                struct  node  *newNode  =  createNode();
                
                newNode->next  =  pHead;  
                pHead  =  newNode;  
        }
        return  pHead;
}


struct  node*  createNode(){
        //  动态申请内存，创建新结点  
        struct  node  *newNode  =  (struct  node*)malloc(sizeof(struct  node));
        if(newNode  !=  NULL){
                //  为新结点的各字段赋值
                scanf("%d",  &newNode->value);  
                newNode->next  =  NULL;  //  好习惯，不要让指针处于未赋值状态
        }
        return  newNode;  
}


void  display(struct  node  *pHead){
        //  请编程实现本函数  
         struct  node  *p  =  NULL;  
         if(pHead)
         	p=pHead;
         	while(p)
         	{
			  printf("%d ",p->value);
			  p=p->next; 
			}

}


struct  node  *  reverse(struct  node  *pHead){
        //  请编程实现本函数  
        if(pHead == NULL || pHead->next == NULL)  //链表为空或者只有头结点
		return pHead;
	struct  node *beg = NULL;       //指向当前结点的上一个结点
	struct  node *mid = pHead;       //指向当前结点
	struct  node *end = pHead->next; //指向当前结点的下一个结点
	while(1){
		mid->next = beg;    //改变指向
		if(end == NULL)     //判断链表是否为空
			break;
		beg = mid;          //后移结点
		mid = end;
		end = end->next;
	}	
	return mid; 
        

}