Two-part question and the parts are pretty different in difficulty.
First, compute the maximum depth of the tree using DFS or BFS, tracking levels from the CEO as level 1. Then, to minimize subtree moves, identify all nodes at depth h+1 and move their entire subtrees directly under the CEO; the number of such nodes is the answer. Alternatively, use a greedy approach: repeatedly move the deepest node's subtree until all nodes are within level h, counting moves.
Pro tip: Clarify that moving a subtree under the CEO reduces the depth of all nodes in that subtree by the same amount, so moving a node at depth h+1 makes its subtree fit within h. Also, mention that the problem can be solved in O(n) time by computing depths and then counting nodes at depth h+1.
Confirm that the tree is rooted at the CEO (level 1), and that moving a subtree means detaching it and attaching it directly under the CEO. Ask if multiple moves can be done sequentially and if the tree structure changes after each move.
Perform a DFS or BFS from the root to find the maximum depth (number of levels). Keep track of the depth of each node, with the CEO at depth 1.
If the maximum depth is less than or equal to h, no moves are needed. Otherwise, find all nodes at depth h+1. Each such node's subtree must be moved to ensure no employee exceeds level h.
The minimum number of moves equals the number of nodes at depth h+1, because moving each such node's subtree directly under the CEO reduces the depth of all nodes in that subtree by h, bringing them within level h. Moving a node at a shallower depth would not fix deeper nodes.
Test with h=1 (only CEO allowed) and h >= max depth. Discuss time complexity: O(n) for traversal and counting, and space complexity O(n) for recursion or queue.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.