You are given an undirected graph with `n` nodes labeled from `1` to `n`, and a list of edges where each edge `[a, b]` connects node `a` and node `b`. Using depth-first search, compute two values: - **(a)** the number of connected components in the graph, and - **(b)** the size (number of nodes) of the largest connected component. Return the answer as an array of exactly two integers: `[number_of_components, size_of_largest_component]`. A connected component is a maximal set of nodes such that there is a path between any two nodes in the set. An isolated node (one with no edges) is itself a connected component of size 1. **Example:** ``` n = 5, edges = [[1,2],[2,3],[4,5]] ``` Components are `{1,2,3}` (size 3) and `{4,5}` (size 2), so the answer is `[2, 3]`. Implement DFS to traverse each component. An iterative (explicit-stack) DFS is preferred over a recursive one here because `n` can be as large as 200,000 and a deep chain would overflow the call stack — the reference solution below uses the iterative form for stack safety.