City Rejuvenation

You are given a directed graph representing a city’s road network with n intersections labeled from 0 to n-1. The road network is described by a list of one-way roads (directed edges) where each road is given as a pair [u, v] indicating a road from intersection u to intersection v.

The city council wants to ensure that starting from the central intersection (node 0), every other intersection is reachable by driving through the available roads. However, the current network might leave some intersections unreachable from node 0.

Your task is to write a function or a class that, given the number of intersections n and a list of roads, returns the minimum number of additional one-way roads that need to be added so that every intersection becomes reachable from intersection 0. If no additional roads are needed, return 0.

Constraints:

• 1 ≤ n ≤ 10^5
• 0 ≤ number of roads ≤ 10^5
• Roads can be added between any two intersections in any direction (even if a road already exists between those two intersections).

Input/Output:

• Input: An integer n representing the number of intersections, and a list of pairs representing the current road connections.
• Output: An integer representing the minimum number of new roads required.

Example:

Suppose n = 4 and roads = [[0, 1], [1, 2]]. Here, intersections 0, 1, and 2 are connected, but intersection 3 is isolated. One possible solution is to add a road from intersection 1 to intersection 3 (i.e., [1, 3]), making all intersections reachable from node 0. Thus, the minimum number of additional roads is 1.

Develop an efficient solution that handles large inputs, keeping in mind the potential number of intersections and roads. Consider suitable algorithms or data structures to ensure your implementation is both time and space efficient.