C++ "Danh sách liên kết đơn"

#include <iostream>
using namespace std;
typedef struct Node {
    int data;
    Node *next;
} Node;

Node *head = NULL;

Node* creatNode(int val){
    Node* temp;
    temp = new Node;
    //temp = malloc(sizeof(Node));
    temp->data = val;
    temp->next = NULL;
//  cout << temp->data << endl;
    return temp;
}

Node* AddHead(int val){
    Node* new_node = creatNode(val);
    if (head == NULL){
        head = new_node;
    } else {
        new_node->next = head;
        head = new_node;
    }
}

void print_llist(){
    Node* p = head;
    while(p != NULL){
        cout << p->data << " ";
        p = p->next;
    }
}

int findNode(int val){
    Node *currentNode = head;
    int currentIndex = 1;
    while (currentNode && currentNode -> data != val) {
        currentNode = currentNode -> next;
        currentIndex++;
    }
    if (currentNode) {
        return currentIndex;
    } else return 0;
}

int main(){
    for(int i = 0; i < 10; i++){
        AddHead(i*i);
    }
    print_llist();
    cout << endl << findNode(64);
    return 0;
}