<div class="_1l1MA">For each node, calculate a list of <code>k</code> values representing <code>k</code> smallest values in the subtree of that node.</div>

<div class="_1l1MA">To check if a node is great enough, get the described list in the first hint for its children and merge them. Since the resulting list may contain more than <code>k</code> elements, pick <code>k</code> smallest values and discard the extra ones.</div>

<div class="_1l1MA">Now check if the merged list has exactly <code>k</code> elements, and the current node's value is greater than the greatest element in the list, then that node is great enough.</div>