| | | 1 | | // -------------------------------------------------------------------------------- |
| | | 2 | | // Copyright (C) 2025 Eugene Eremeev (also known as Yevhenii Yeriemeieiv). |
| | | 3 | | // All Rights Reserved. |
| | | 4 | | // -------------------------------------------------------------------------------- |
| | | 5 | | // This software is the confidential and proprietary information of Eugene Eremeev |
| | | 6 | | // (also known as Yevhenii Yeriemeieiv) ("Confidential Information"). You shall not |
| | | 7 | | // disclose such Confidential Information and shall use it only in accordance with |
| | | 8 | | // the terms of the license agreement you entered into with Eugene Eremeev (also |
| | | 9 | | // known as Yevhenii Yeriemeieiv). |
| | | 10 | | // -------------------------------------------------------------------------------- |
| | | 11 | | |
| | | 12 | | namespace LeetCode.Algorithms.ShortestDistanceAfterRoadAdditionQueries1; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public class ShortestDistanceAfterRoadAdditionQueries1BreadthFirstSearch : IShortestDistanceAfterRoadAdditionQueries1 |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(n * q) |
| | | 19 | | /// Space complexity - O(n + q) |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="n"></param> |
| | | 22 | | /// <param name="queries"></param> |
| | | 23 | | /// <returns></returns> |
| | | 24 | | public int[] ShortestDistanceAfterQueries(int n, int[][] queries) |
| | 2 | 25 | | { |
| | 2 | 26 | | var adjacencyList = new List<int>[n]; |
| | | 27 | | |
| | 22 | 28 | | for (var i = 0; i < n; i++) |
| | 9 | 29 | | { |
| | 9 | 30 | | adjacencyList[i] = []; |
| | 9 | 31 | | } |
| | | 32 | | |
| | 18 | 33 | | for (var i = 0; i < n - 1; i++) |
| | 7 | 34 | | { |
| | 7 | 35 | | adjacencyList[i].Add(i + 1); |
| | 7 | 36 | | } |
| | | 37 | | |
| | 2 | 38 | | var distances = new int[n]; |
| | | 39 | | |
| | 18 | 40 | | for (var i = 1; i < distances.Length; i++) |
| | 7 | 41 | | { |
| | 7 | 42 | | distances[i] = i; |
| | 7 | 43 | | } |
| | | 44 | | |
| | 2 | 45 | | var result = new int[queries.Length]; |
| | | 46 | | |
| | 14 | 47 | | for (var i = 0; i < queries.Length; i++) |
| | 5 | 48 | | { |
| | 5 | 49 | | var fromNode = queries[i][0]; |
| | 5 | 50 | | var toNode = queries[i][1]; |
| | | 51 | | |
| | 5 | 52 | | adjacencyList[fromNode].Add(toNode); |
| | | 53 | | |
| | 5 | 54 | | if (distances[fromNode] + 1 < distances[toNode]) |
| | 5 | 55 | | { |
| | 5 | 56 | | distances[toNode] = distances[fromNode] + 1; |
| | | 57 | | |
| | 5 | 58 | | UpdateDistancesFrom(adjacencyList, distances, toNode); |
| | 5 | 59 | | } |
| | | 60 | | |
| | 5 | 61 | | result[i] = distances[n - 1] == int.MaxValue ? -1 : distances[n - 1]; |
| | 5 | 62 | | } |
| | | 63 | | |
| | 2 | 64 | | return result; |
| | 2 | 65 | | } |
| | | 66 | | |
| | | 67 | | private static void UpdateDistancesFrom(List<int>[] adjacencyList, int[] distances, int startNode) |
| | 5 | 68 | | { |
| | 5 | 69 | | var queue = new Queue<int>(); |
| | | 70 | | |
| | 5 | 71 | | queue.Enqueue(startNode); |
| | | 72 | | |
| | 12 | 73 | | while (queue.Count > 0) |
| | 7 | 74 | | { |
| | 7 | 75 | | var currentNode = queue.Dequeue(); |
| | | 76 | | |
| | 25 | 77 | | foreach (var neighbor in adjacencyList[currentNode] |
| | 11 | 78 | | .Where(neighbor => distances[currentNode] + 1 < distances[neighbor])) |
| | 2 | 79 | | { |
| | 2 | 80 | | distances[neighbor] = distances[currentNode] + 1; |
| | | 81 | | |
| | 2 | 82 | | queue.Enqueue(neighbor); |
| | 2 | 83 | | } |
| | 7 | 84 | | } |
| | 5 | 85 | | } |
| | | 86 | | } |