Add two numbers represented by linked lists

#include <iostream>
#include <string>

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

void push(node** head_ref, int new_data)
{
node* new_node = new node();
new_node->data = new_data;
new_node->next = *head_ref;
*head_ref = new_node;
};

int getSize(node* n)
{
int size = 0;
while(n)
{
n = n->next;
size++;
}

return size;
};

node* addSameSize(node* l1, node* l2, int* carry)
{
if (l1 == NULL)
return NULL;

int sum;
node* result = new node();
result->next = addSameSize(l1->next, l2->next, carry);
sum = l1->data + l2->data + *carry;
*carry = sum / 10;
result->data = sum % 10;

return result;

};

void swapPointer(node** n1, node** n2)
{
node* t = *n1;
*n1 = *n2;
*n2 = t;
};

void addCarryToRemaining(node* l1, node* cur, int* carry, node** result)
{
int sum;
if (l1 != cur)
{
addCarryToRemaining(l1->next, cur, carry, result);

sum = l1->data + *carry;
*carry = sum / 10;
sum %= 10;
push(result, sum);
}
};

void addList(node* l1, node* l2, node** result) // result should be passed as pointer to pointer
{

if (l1 == NULL)
{
*result = l2;
return;
}
if (l2 == NULL)
{
*result = l1;
return;
}

int size1 = getSize(l1);
int size2 = getSize(l2);

int carry = 0;

if (size1 == size2)
*result = addSameSize(l1, l2, &carry);
else
{
int diff = std::abs(size1 - size2);
if (size1 < size2)
swapPointer(&l1, &l2);
node* cur;
for (cur = l1; diff--; cur = cur->next);

*result = addSameSize(cur, l2, &carry);

// add carry to remaining
addCarryToRemaining(l1, cur, &carry, result);

if (carry)
push(result, carry);
}
};

void printList(node* n)
{
while (n)
{
std::cout << n->data << " ";
n = n->next;
}
std::cout << "\n";
return;
};

int main()
{
int l1[] = {9, 9, 9};
int l2[] = {1, 8};

int size1 = sizeof(l1) / sizeof(l1[0]);
int size2 = sizeof(l2) / sizeof(l2[0]);

node* head1 = NULL, *head2 = NULL, *result = NULL;

int i;
for (int i = size1 - 1; i >= 0; --i)
push(&head1, l1[i]);
for (int i = size2 - 1; i >= 0; --i)
push(&head2, l2[i]);

addList(head1, head2, &result);
printList(result);

return 0;
}