ll.c

#include <stdio.h>
#include <stdlib.h>


typedef struct Node {
    struct Node *prev;
    struct Node *next;
    int data;
} Node;

int insertAtHead(Node **head, int data) {
    Node *newHead = malloc(sizeof(Node));
    if (!newHead) return 1;

    newHead->data=data;
    newHead->next=*head;
    (*head)->prev=newHead;
    *head=newHead;
    return 0;
}

Node* find(Node** head, int target) {
    Node *cur = malloc(sizeof(Node));
    if (!cur) return cur;

    cur = *head;
    while (cur) {
        if (cur->data == target) break;
        cur = cur->next;
    }
    return cur;
}

int deleteNode(Node **head, Node *node) {
    if (!node || !head) return 1;

    if (*head == node) {
        *head = node->next;
        node->next->prev = *head;
    } else {
        Node *adj = malloc(sizeof(Node));
        if (!adj) return 1;

        adj = node->prev;
        adj->next = node->next;
        adj = node->next;
        if (adj) adj->prev = node->prev;
    }

    free(node);
    return 0;
}

//assume singly linked
int reverseList(Node **head) {
    if (!head && !*head) return 1;

    Node *cur = malloc(sizeof(Node));
    Node *next = malloc(sizeof(Node));
    Node *temp = malloc(sizeof(Node));
    cur = *head;
    next = cur->next;

    while (next) {
        temp = next->next;
        next->next = cur;
        cur = next;
        next= temp;
    }
    (*head)->next = NULL;
    *head = cur;
    return 0;
}

void printList(Node *node) {
    if (!node) return;

    Node *cur = malloc(sizeof(Node));
    if (!cur) return;

    cur = node;
    while (cur) {
        printf("%d ", cur->data);
        cur = cur->next;
    }
    printf("\n");
    return;
}