You are given a binary tree T = (V, E) (in adjacency list format), along with a designated root node r ∈ V. Recall that u is said to be an ancestor of v in the rooted tree, if the path from r to v in T passes through u.
You wish to preprocess the tree so that queries of the form “is u an ancestor of v?” can be answered in constant time. The preprocessing itself should take linear time. How can this be done?
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