Question

I’m sorry that was my first time for asking question in stackoverflow. I just read the faq and knew I disobeyed the rules. I was not just coping and pasting the questions. I use an in-order traverse method to do the recursion and check whether the node is a multiple of five and I don’t know what to do next. Should I use a flag to check something?

void findNodes(BSTNode<Key,E> *root) const
{
    if(root==NULL) return;
    else
    {
        if(root->key()%5==0)//I know it's wrong, but I don't know what to do
        {
            findNodes(root->left());
            cout<<root->key()<<" ";
            findNodes(root->right());
        }
        else
        {
            findNodes(root->left());
            findNodes(root->right());
        }

    }
}

Answer 1

Printing nodes whose grandparent is a multiple of 5 is complicated as you have to look “up” the tree. It is easier if you look at the problem as find all the nodes who are a multiple of 5 and print their grandchildren, as you only have to go down the tree.

void printGrandChildren(BSTNode<Key,E> *root,int level) const{
    if(!root) return;
    if(level == 2){
         cout<<root->key()<<" ";
         return;


    }else{
        printGrandChildren(root->left(),level+1);
        printGrandChildren(root->right(),level+1);

     }

}

Then modify your findNodes to

void findNodes(BSTNode<Key,E> *root) const
{
    if(root==NULL) return;
    else
    {
        if(root->key()%5==0)
        {
            printGrandChildren(root,0);
        }
        else
        {
            findNodes(root->left());
            findNodes(root->right());
        }

    }
}