#include 
     
      #include 
      
       typedef int ElementType;struct DoubleCircularListNode{    ElementType Element;    struct DoubleCircularListNode *Prior;    struct DoubleCircularListNode *Next;};struct DoubleCircularListNode* DoubleCircularListInit(){    struct DoubleCircularListNode* ListHead = malloc(sizeof(struct DoubleCircularListNode));    ListHead -> Prior = ListHead -> Next = ListHead;    return ListHead;}int DoubleCircularListNodeAdd(struct DoubleCircularListNode *ListHead,ElementType ToBeInsert){    struct DoubleCircularListNode* TmpCell;    struct DoubleCircularListNode* LastNode;    TmpCell = malloc(sizeof(struct DoubleCircularListNode));    TmpCell -> Element = ToBeInsert;    LastNode = ListHead -> Prior;    TmpCell -> Prior = LastNode;    TmpCell -> Next = ListHead;    ListHead -> Prior = LastNode -> Next = TmpCell;    return 0;}int DoubleCircularListIsEmpty(struct DoubleCircularListNode *ListHead){    return (ListHead->Next == ListHead);}int DoubleCircularListIsLast(struct DoubleCircularListNode *PtrToNode,struct DoubleCircularListNode *ListHead){    return (PtrToNode -> Next == ListHead);}//Warning:ensure the return pointer doesn't point to ListHeadstruct DoubleCircularListNode* DoubleCircularListNodeFind(ElementType ToBeFind,struct DoubleCircularListNode *ListHead){    struct DoubleCircularListNode* Pointer;    Pointer = ListHead -> Next;    while(Pointer != ListHead && Pointer -> Element != ToBeFind)    {        Pointer = Pointer -> Next;    }    return Pointer;}int DoubleCircularListNodeDelete(ElementType ToBeDelete,struct DoubleCircularListNode *ListHead){    struct DoubleCircularListNode *Pointer;    Pointer = DoubleCircularListNodeFind(ToBeDelete,ListHead);        if(Pointer == ListHead)    {        return 1;    }    else if(Pointer -> Prior == ListHead)    {        ListHead -> Prior = ListHead -> Next = ListHead;        free(Pointer);        return 0;    }    else    {        Pointer -> Next -> Prior = Pointer -> Prior;        Pointer -> Prior -> Next = Pointer -> Next;        free(Pointer);        return 0;    }    return 1;}int MakeDoubleCircularListEmpty(struct DoubleCircularListNode *ListHead){    struct DoubleCircularListNode *Pointer_1;    struct DoubleCircularListNode *Pointer_2;    if(ListHead != NULL)    {        Pointer_1 = ListHead;        Pointer_2 = ListHead -> Next;        while(Pointer_2 != ListHead)        {            Pointer_1 = Pointer_2;            Pointer_2 = Pointer_2 -> Next;            free(Pointer_1);        }        ListHead -> Prior = ListHead -> Next = ListHead;    }    else    {        return 1;    }    return 0;}int DoubleCircularListDelete(struct DoubleCircularListNode *ListHead){    MakeDoubleCircularListEmpty(ListHead);    free(ListHead);    return 0;}int DoubleCircularListNodeInsert(struct DoubleCircularListNode *ListHead,ElementType ToBeInsert,struct DoubleCircularListNode *PositionBeforeToBeInsert){    struct DoubleCircularListNode* TmpCell;    TmpCell = malloc(sizeof(struct DoubleCircularListNode));    TmpCell -> Element = ToBeInsert;        if(TmpCell == NULL)    {        return 1;    }        TmpCell -> Prior = PositionBeforeToBeInsert;    TmpCell -> Next = PositionBeforeToBeInsert -> Next;    PositionBeforeToBeInsert -> Next -> Prior = TmpCell;    PositionBeforeToBeInsert -> Next = TmpCell;    return 0;}int main(){    struct DoubleCircularListNode* ListHead;    ListHead = DoubleCircularListInit();    DoubleCircularListNodeInsert(ListHead,1,ListHead);    DoubleCircularListNodeInsert(ListHead,3,DoubleCircularListNodeFind(1,ListHead));    DoubleCircularListNodeAdd(ListHead,4);    DoubleCircularListNodeInsert(ListHead,2,DoubleCircularListNodeFind(1,ListHead));    int test = DoubleCircularListNodeDelete(2,ListHead);    printf("test = %d %d\n",test,ListHead -> Next -> Element);    printf("%d\n",ListHead -> Next -> Next -> Element);    //printf("%d\n",ListHead -> Next -> Next -> Next -> Element);    test = DoubleCircularListNodeDelete(2,ListHead);    printf("test = %d %d\n",test,ListHead -> Next -> Next -> Element);    //printf("%d\n",ListHead -> Next -> Next -> Next -> Element);    //printf("%d\n",DoubleCircularListNodeFind(3,ListHead)->Element);    DoubleCircularListDelete(ListHead);    return 0;}