Find Building Where Alice and Bob Can Meet

For each query (a,b) return the leftmost index j > max(a,b) such that heights[j] > heights[a] and heights[j] > heights[b], or -1 if no such building exists. The core challenge is answering many "first element to the right exceeding a given threshold" queries efficiently, typically via next-greater/monotonic-stack preprocessing and jump pointers (binary lifting).