DoubleLinkedList

typedef enum {false,true} bool;
typedef int Data;
 
typedef struct _Node
{
    Data item;
    struct _Node *next;
    struct _Node *prev;
} Node;
 
typedef struct
{
    Node *head;
    int len;
} DoubleLinkedList;
 
void InitList(DoubleLinkedList *plist){
    Node* dummy1, *dummy2;
    dummy1 = (Node*)malloc(sizeof(Node));
    dummy2 = (Node*)malloc(sizeof(Node));
 
    dummy1->prev = NULL;
    dummy1->next = dummy2;
    dummy2->prev = dummy1;
    dummy2->next = NULL;
 
    plist->head = dummy1;
    plist->len = 0;
}
 
void InsertMiddle(DoubleLinkedList *plist, int pos, Data item){
    Node* cur, *newNode;
 
    newNode= (Node*)malloc(sizeof(Node));
    newNode->item = item;
    newNode->prev = NULL;
    newNode->next = NULL;
 
    cur = plist->head;
    for(int i=0; i < pos;i++){
        cur= cur->next;
    }
 
    newNode->prev = cur;
    newNode->next = cur->next;
    cur->next->prev = newNode;
    cur->next = newNode;
    plist->len++;
}
 
void RemoveMiddle(DoubleLinkedList *plist, int pos){
    Node* cur, *temp;
 
    if(IsEmpty(plist) || pos< 0 || pos >= plist->len) exit(1);
 
    cur = plist->head;
    for(int i=0; i < pos;i++){
        cur = cur->next;
    }
 
    temp = cur->next;
    temp->next->prev = cur;
    cur->next = temp->next;
 
    plist->len--;
    free(temp);
}