All about pointers & linked lists

//Trần Việt Anh - 6:00PM - 15/4/2019
#include<iostream>

using namespace std;

struct Node
{
    int value;
    Node* next;
};


Node* initLinkedList(int n, int arr[]) {
    Node* p[n];
    for (int i = 0; i < n; i++)
        p[i] = new Node();
    for (int i = 0; i < n - 1; i++) {
        p[i] -> value = arr[i];
        p[i] -> next = p[i + 1];
    }
    p[n - 1] -> value = arr[n - 1];
    p[n - 1] -> next = NULL;
    return p[0];
}

void print(Node* head)
{
    Node *n;
    n = head;
    while (n != NULL) {
        cout <<  n -> value << " ";
        n = n -> next;
    }
    cout << endl;
}

Node* insertHead(Node* head, int value)
{
    Node *result;
    result -> value = value;
    result -> next = head;
    return result;
}

Node* insertTail(Node* head, int value)
{
    Node *n;
    n = head;
    if (n == NULL) {
        head = new Node();
        head -> value = value;
        head -> next = NULL;
    }
    else {
        while (n -> next != NULL) n = n -> next;
        Node *insertNode;
        insertNode = new Node();
        insertNode -> value = value;
        insertNode -> next = NULL;
        n -> next = insertNode;
    }
    return head;
}

Node* deleteNode(Node* head, int pos)
{
    int currentPos = 0;
    if (pos == 0)
        return head -> next;
    Node *n = head;
    while (currentPos < pos - 1) {
        n = n -> next;
        currentPos++;
    }
    n -> next = n -> next -> next;
    return head;
}

int getValue(Node* head, int pos)
{
    int currentPos = 0;
    Node *n = head;
    while (currentPos < pos) {
        n = n -> next;
        currentPos++;
    }
    return n -> value; // Change this line
}

Node* deleteDuplicates(Node* head) {
    Node* n;
    n = head;
    Node* temp;
    temp = head;
    while (n != NULL) {
        bool foundDuplicate = false;
        while (n -> next != NULL && n -> next -> value == temp -> value) {
            foundDuplicate = true;
            n = n -> next;
        }
        if (foundDuplicate) {
            cout << "found" << endl;
            temp -> next = n -> next;
            temp = n -> next;
        }
        else return head;
        n = n -> next;
    }
    return head;
}

Node* insert(Node* head, int value) {
    Node* n = head;
    if (n -> value >= value) {
        Node* insertNode = new Node();
        insertNode -> value = value;
        insertNode -> next = n;
        return insertNode;
    }
    while (n -> next !=  NULL && n -> next -> value <= value) n = n -> next;
    Node* insertNode = new Node();
    insertNode -> value = value;
    insertNode -> next = n -> next;
    n -> next = insertNode;
    return head;
}

int getNodeValue(Node* head, int index) {
    int pos = 0;
    Node* n = head;
    while (pos < index) {
        n = n -> next;
        pos++;
    }
    return n -> value;
}

Node* convert(Node* head)
{
    if (head == NULL) return head;
    Node* tail = head; int length = 1;
    Node* start = head;
    Node* temp = head;
    while (tail -> next != NULL) {
        tail = tail -> next;
        length++;
    }
    for (int i = length / 2 - 1; i > 0; i--) {
        for (int j = 0; j < i; j++) {
            temp = temp -> next;
            tail -> next = new Node(); tail = tail -> next;
            tail -> value = temp -> value;
        }
        temp = temp -> next; start -> next = temp;
        start = temp;
        for (int j = 0; j < i; j++) {
            temp = temp -> next;
            tail -> next = new Node(); tail = tail -> next;
            tail -> value = temp -> value;
        }
        temp = temp -> next; start -> next = temp;
        start = temp;
    }
    return head;
}

int main() {

    Node* head;
    int arr[6] = {1, 3, 5, 2, 4, 6};

    head = initLinkedList(6, arr);

    cout << "Initialize successful" << endl;

    print(head);

    head = insertHead(head, 5);
    print(head);

    head = insertTail(head, 2);
    print(head);

    head = deleteNode(head, 0);
    print(head);

    cout << getValue(head, 2) << endl;

    head = deleteDuplicates(head);
    print(head);

    head = insert(head, 1);
    print(head);

    head = convert(head);
    print(head);
}