Question

I tried to answer the following 2 question, they are from a Java course test, but it is a little confusing because of the recursive that I’m probably need to use.

The first one is a method that receive a root of a binary tree and returns the maximum value on tree. (example in figure A).

This question (and the second) says only complete in the missing lines:

public static int maxInTree (Node root)
{
    if (root == null)
        return 0;
    if ((root.getLeftSon() == null) && (root.getRightSon() == null))
        ______________________    // I think that here: *return 1*;
    if (root.getLeftSon() == null)
    return _________________
    if (___________ == null)    // I think that here: *root.getRightSon()*
    _______________________________-
    return max______________________________
}

The second question says: do the same as the first question BUT for a sorted binary search tree.

public static int maxInSearchTree (Node r)
{
    if (r == null)
        return 0;
    if (r.getRightSon() == null)
        __________________________
    return _______________________________
}

You can assume there is a method to pullout the father: getNumber().

thnx !!

Answer 1

I assume that getNumber() gives the value (not the father).

public static int maxInTree (Node root)
{
    if (root == null)
        return 0;
    if ((root.getLeftSon() == null) && (root.getRightSon() == null))
        return root.getNumber();
    if (root.getLeftSon() == null)
        return max(root.getNumber(), maxInTree(root.getRightSon()));
    if (root.getRightSon() == null)
        return max(root.getNumber(), maxInTree(root.getLeftSon()));
    return max(root.getNumber(),
        max(maxInTree(root.getLeftSon()),maxInTree(root.getRightSon())));
}

public static int maxInSearchTree (Node r)
{
    if (r == null)
        return 0;
    if (r.getRightSon() == null)
        return r.getNumber();
    return maxInSearchTree(r.getRightSon());
}