链表相关的操作

typedef struct node {
    struct node* next;
    int data;
}Element;

Element* createSingleLinkedList(int* arr,int size) {
    Element *head = NULL, *pre = NULL,*p = NULL;
    for (int i = 0; i < size; i++) {
        p = (Element*)malloc(sizeof(Element));
        if (p == NULL) {
            return NULL;
        }
        else {
            p->data = arr[i];
            p->next = NULL;
            if (head == NULL) {
                head = pre = p;
            }
            else {
                pre = pre->next = p;
            }
        }
    }
    return head;
}

Element* createSingleLinkedWithoutHead(int *arr,int size) {
    Element *head = NULL,*pre = NULL,*p = NULL;
    p = (Element*)malloc(sizeof(Element));
    if (p == NULL) {
        return NULL;
    }
    p->data = -1;
    p->next = NULL;
    head = pre = p;
    for (int i = 0; i < size; i++) {
        p = (Element*)malloc(sizeof(Element));
        if (p == NULL) {
            return NULL;
        }
        p->data = arr[i];
        p->next = NULL;
        pre = pre->next = p;
    }
    return head;
}

Element* removeVal(Element* head, int val) {
    for (Element* p = head, *pre = head; p != NULL;) {
        if (p->data == val) {
            if (p == head) {
                head = head->next;
                delete(p);
                p = pre = head;
            }
            else {
                pre->next = p->next;
                delete(p);
                p = pre->next;
            }
        }else{
            pre = p;
            p = p->next;
        }
    }
    return head;
}

Element* removeElements(Element *head,int val) {
    if (head == NULL) {
        return head;
    }
    head->next = removeElements(head->next,val);
    return head->data == val ? head->next : head;
}

void deleteNode(Element *node) {
    *node = *(node->next);
}