| | | 1 | | // -------------------------------------------------------------------------------- |
| | | 2 | | // Copyright (C) 2026 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.MinimumNumberOfPeopleToTeach; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public sealed class MinimumNumberOfPeopleToTeachGreedyCounting : IMinimumNumberOfPeopleToTeach |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(m * n), where m is the number of users and n is the number of languages |
| | | 19 | | /// Space complexity - O(m * n), where m is the number of users and n is the number of languages |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="languagesCount"></param> |
| | | 22 | | /// <param name="languages"></param> |
| | | 23 | | /// <param name="friendships"></param> |
| | | 24 | | /// <returns></returns> |
| | | 25 | | public int MinimumTeachings(int languagesCount, int[][] languages, int[][] friendships) |
| | 2 | 26 | | { |
| | 2 | 27 | | var usersCount = languages.Length; |
| | | 28 | | |
| | 2 | 29 | | Span<bool> userLanguages = stackalloc bool[usersCount * languagesCount]; |
| | | 30 | | |
| | 18 | 31 | | for (var i = 0; i < usersCount; i++) |
| | 7 | 32 | | { |
| | 41 | 33 | | foreach (var language in languages[i]) |
| | 10 | 34 | | { |
| | 10 | 35 | | userLanguages[GetUserLanguageIndex(i, language - 1, languagesCount)] = true; |
| | 10 | 36 | | } |
| | 7 | 37 | | } |
| | | 38 | | |
| | 2 | 39 | | Span<bool> usersToTeach = stackalloc bool[usersCount]; |
| | | 40 | | |
| | 2 | 41 | | Span<int> usersToTeachIndices = stackalloc int[usersCount]; |
| | | 42 | | |
| | 2 | 43 | | var usersToTeachCount = 0; |
| | | 44 | | |
| | 20 | 45 | | foreach (var friendship in friendships) |
| | 7 | 46 | | { |
| | 7 | 47 | | var userA = friendship[0] - 1; |
| | 7 | 48 | | var userB = friendship[1] - 1; |
| | | 49 | | |
| | 7 | 50 | | var isOverlap = false; |
| | | 51 | | |
| | 38 | 52 | | for (var language = 0; language < languagesCount; language++) |
| | 15 | 53 | | { |
| | 15 | 54 | | if (!userLanguages[GetUserLanguageIndex(userA, language, languagesCount)] || |
| | 15 | 55 | | !userLanguages[GetUserLanguageIndex(userB, language, languagesCount)]) |
| | 12 | 56 | | { |
| | 12 | 57 | | continue; |
| | | 58 | | } |
| | | 59 | | |
| | 3 | 60 | | isOverlap = true; |
| | | 61 | | |
| | 3 | 62 | | break; |
| | | 63 | | } |
| | | 64 | | |
| | 7 | 65 | | if (isOverlap) |
| | 3 | 66 | | { |
| | 3 | 67 | | continue; |
| | | 68 | | } |
| | | 69 | | |
| | 4 | 70 | | if (!usersToTeach[userA]) |
| | 3 | 71 | | { |
| | 3 | 72 | | usersToTeach[userA] = true; |
| | 3 | 73 | | usersToTeachIndices[usersToTeachCount] = userA; |
| | 3 | 74 | | usersToTeachCount++; |
| | 3 | 75 | | } |
| | | 76 | | |
| | 4 | 77 | | if (!usersToTeach[userB]) |
| | 3 | 78 | | { |
| | 3 | 79 | | usersToTeach[userB] = true; |
| | 3 | 80 | | usersToTeachIndices[usersToTeachCount] = userB; |
| | 3 | 81 | | usersToTeachCount++; |
| | 3 | 82 | | } |
| | 4 | 83 | | } |
| | | 84 | | |
| | 2 | 85 | | if (usersToTeachCount == 0) |
| | 0 | 86 | | { |
| | 0 | 87 | | return 0; |
| | | 88 | | } |
| | | 89 | | |
| | 2 | 90 | | var mostCommonLanguageCount = 0; |
| | | 91 | | |
| | 14 | 92 | | for (var language = 0; language < languagesCount; language++) |
| | 5 | 93 | | { |
| | 5 | 94 | | var currentLanguageCount = 0; |
| | | 95 | | |
| | 42 | 96 | | for (var i = 0; i < usersToTeachCount; i++) |
| | 16 | 97 | | { |
| | 16 | 98 | | var user = usersToTeachIndices[i]; |
| | | 99 | | |
| | 16 | 100 | | if (userLanguages[GetUserLanguageIndex(user, language, languagesCount)]) |
| | 8 | 101 | | { |
| | 8 | 102 | | currentLanguageCount++; |
| | 8 | 103 | | } |
| | 16 | 104 | | } |
| | | 105 | | |
| | 5 | 106 | | mostCommonLanguageCount = Math.Max(mostCommonLanguageCount, currentLanguageCount); |
| | 5 | 107 | | } |
| | | 108 | | |
| | 2 | 109 | | return usersToTeachCount - mostCommonLanguageCount; |
| | 2 | 110 | | } |
| | | 111 | | |
| | | 112 | | private static int GetUserLanguageIndex(int user, int language, int languagesCount) |
| | 49 | 113 | | { |
| | 49 | 114 | | return (user * languagesCount) + language; |
| | 49 | 115 | | } |
| | | 116 | | } |