程序填空题：Delete a node from a linked list

The program below contains the **finding** and **deleting** operations of the Linked List **without** dummy head node.

The definition of the linked list is:
```
struct Node{
int data;
struct Node *next;
};
```
The nodes of linked list are numbered sequentially from `1`. (It means we count the nodes as `1,2,3,...` not `0,1,2,...`)

The functions are described as:

`struct Node* findByIndex(struct Node *head, int index)` ，search for the node whose index number is `index` and return its **address**. Return `NULL` if failed.

`int deleteByIndex(struct Node **phead, int index, int *pitem)` , copy the value of node whose index number is `index` to the variable which `pitem` points to, and then delete the node. Return `1` if succeeded and `0` if failed.

e.g. for a linked list **head->12->34->56** ,

`findByIndex(head, 2)` will return the address of node `34`, and `deleteByIndex(&head, 2, &item)` wil make the list become **head->12->56** and copy `34` into variable `item`.

Fill in the blanks to complete the function：

```c++
#include
#include
struct Node{
int data;
struct Node *next;
};
struct Node* initList(){ return NULL; }
void printList(struct Node* head){
/* details omitted */
}
struct Node* createNode(int data){
struct Node *p;
p = (struct Node*)malloc(sizeof(struct Node));
if(!p) return NULL;
p->data = data;
p->next = NULL;
return p;
};

struct Node* findByIndex(struct Node *head, int index){
int i;
if(head==NULL || index < 1) return NULL;
for(i=1; @@[ head && inext,i++);
return head;
}

int deleteByIndex(struct Node **phead, int index, int *pitem){
struct Node *tmp;
if(*phead==NULL || index < 1) return 0;
else if(index == 1){
tmp = *phead;
*phead = @@[ tmp->next ](1) ;
}
else{
struct Node *p;
p = findByIndex(*phead, @@[ index-1](1) );
if(@@[ !p || p->next==NULL ](2)) return 0;
tmp = @@[ p->next ](1) ;
@@[ p->next ](1) = tmp->next;
}
*pitem = tmp->data;
free(tmp);
return 1;
}
```






答案：
第1空： head && i
第2空： tmp->next

第3空： index-1

第4空： !p || p->next==NULL

第5空： p->next

第6空： p->next