CSC403: Tree code: Nullable [20/29]

    public int size () {
        return size (root);
    }
    private static int size (Node x) {
        if (x == null) return 0;
        int sz = 1;
        sz += size (x.left);
        sz += size (x.right);
        return sz;
    }

Back to the version with one variable.

Note that it does not matter when we add 1 to sz, since we don't carry the intermediate values around as parameters.

In this code, we make the call, then check for null.

The variable x is nullable (may be assigned null)

Lets call this the nullable version.

We might also call it optimistic, or Just do it!