Package g3601_3700.s3607_power_grid_maintenance

Class Solution

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public final class Solution

    3607 - Power Grid Maintenance.

    Medium

    You are given an integer c representing c power stations, each with a unique identifier id from 1 to c (1‑based indexing).

    These stations are interconnected via n bidirectional cables, represented by a 2D array connections, where each element <code>connectionsi = u<sub>i</sub>, v<sub>i</sub></code> indicates a connection between station <code>u<sub>i</sub></code> and station <code>v<sub>i</sub></code>. Stations that are directly or indirectly connected form a power grid.

    Initially, all stations are online (operational).

    You are also given a 2D array queries, where each query is one of the following two types:

    • [1, x]: A maintenance check is requested for station x. If station x is online, it resolves the check by itself. If station x is offline, the check is resolved by the operational station with the smallest id in the same power grid as x. If no operational station exists in that grid, return -1.

    • [2, x]: Station x goes offline (i.e., it becomes non-operational).

    Return an array of integers representing the results of each query of type [1, x] in the order they appear.

    Note: The power grid preserves its structure; an offline (non‑operational) node remains part of its grid and taking it offline does not alter connectivity.

    Example 1:

    Input: c = 5, connections = [1,2,2,3,3,4,4,5], queries = [1,3,2,1,1,1,2,2,1,2]

    Output: 3,2,3

    Explanation:

    • Initially, all stations {1, 2, 3, 4, 5} are online and form a single power grid.

    • Query [1,3]: Station 3 is online, so the maintenance check is resolved by station 3.

    • Query [2,1]: Station 1 goes offline. The remaining online stations are {2, 3, 4, 5}.

    • Query [1,1]: Station 1 is offline, so the check is resolved by the operational station with the smallest id among {2, 3, 4, 5}, which is station 2.

    • Query [2,2]: Station 2 goes offline. The remaining online stations are {3, 4, 5}.

    • Query [1,2]: Station 2 is offline, so the check is resolved by the operational station with the smallest id among {3, 4, 5}, which is station 3.

    Example 2:

    Input: c = 3, connections = [], queries = [1,1,2,1,1,1]

    Output: 1,-1

    Explanation:

    • There are no connections, so each station is its own isolated grid.

    • Query [1,1]: Station 1 is online in its isolated grid, so the maintenance check is resolved by station 1.

    • Query [2,1]: Station 1 goes offline.

    • Query [1,1]: Station 1 is offline and there are no other stations in its grid, so the result is -1.

    Constraints:

    • <code>1 <= c <= 10<sup>5</sup></code>

    • <code>0 <= n == connections.length <= min(10<sup>5</sup>, c * (c - 1) / 2)</code>

    • connections[i].length == 2

    • <code>1 <= u<sub>i</sub>, v<sub>i</sub><= c</code>

    • <code>u<sub>i</sub> != v<sub>i</sub></code>

    • <code>1 <= queries.length <= 2 * 10<sup>5</sup></code>

    • queries[i].length == 2

    • queries[i][0] is either 1 or 2.

    • 1 &lt;= queries[i][1] &lt;= c

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final IntArray processQueries(Integer c, Array<IntArray> connections, Array<IntArray> queries)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait