Largest Independent Set Problem (GFG)

pair<int, int> compute(Node *root) {
    if(root == nullptr) return {0, 0};
    pair<int, int> l = compute(root -> left);
    pair<int, int> r = compute(root -> right);
    pair<int, int> curr = {1 + l.second + r.second, max(l.first, l.second) + max(r.first, r.second)};
    return curr;
}

int LISS(Node *root)
{
    //Code here
    pair<int, int> ans = compute(root);
    return max(ans.first, ans.second);
}