2130. Maximum Twin Sum of a Linked List

int pairSum(ListNode* head) {
        int count = 0;
        ListNode * temp  = head;
        while(temp->next!=nullptr)
        {
            count++;
            temp = temp->next;
        }
        int size = count+1;
        int *arr = new int [size];
        temp = nullptr;
        temp = head;
        int i=0;
        while(temp!=nullptr)
        {
            arr[i] = temp->val;
            i++;
            temp = temp->next;
        }        
        temp = nullptr;
        temp = head;
        int sum = 0;
        i = 0;
        while(temp->next!=nullptr && i<=(size/2))
        {
            int index = (size-1-i);
            int q = temp->val + arr[index];
            cout << index ;
            //cout << temp->val << arr[index] << endl;
            if(q>sum)
            {
                sum = q;
            }
            i++;
            temp = temp->next;
        }
        return sum;
    }