Dedupe titles in per-shelf viewport

You are rendering a streaming app home page. - The home page consists of **shelves** displayed from top to bottom. - Each shelf contains a list of `titleId` values (integers). - Each shelf’s horizontal viewport can show at most **X** titles. - Assume the vertical viewport is unlimited (i.e., you process shelves in order, top to bottom). Implement a function that **filters titles while preserving order** under the following deduplication rules: 1. **Global dedupe within the visible region:** - While building the **first `X` output titles** for a shelf, you must **skip** any `titleId` that has already appeared in the **visible region** (first `X` output titles) of any earlier shelf. 2. **Local dedupe after the visible region:** - After a shelf has already produced `X` output titles, continue outputting additional titles from that shelf, but now **only dedupe within the same shelf** (i.e., skip repeats that have already been output in this shelf). - Global deduplication no longer applies past position `X` within a shelf. ### Function signature - Input: `shelves: List[List[int]]`, `X: int` - Output: `List[List[int]]` (the filtered shelves) ### Notes - Preserve the original relative order of titles within each shelf. - If a shelf has fewer than `X` eligible titles (after global dedupe), it may output fewer than `X` titles. ### Example If `X = 2` and shelves are: - Shelf 1: `[1, 2, 1, 3]` - Shelf 2: `[2, 4, 2, 5]` Then: - Shelf 1 visible region (first 2 outputs) becomes `[1, 2]` (global seen = `{1,2}`), then locally can output `3` (skipping the repeated `1`). - Shelf 2 visible region cannot use `2` (already globally visible), so it outputs `[4, 2]` as its first 2 outputs (4 is new globally visible; once the shelf has hit `X` outputs, `2` is allowed even though it was globally visible). After that it can output `5`. So the output is `[[1, 2, 3], [4, 2, 5]]`. Specify and implement the algorithm.