| | | 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.NumberOfGoodPairs; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public class NumberOfGoodPairsDictionary : INumberOfGoodPairs |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(n) |
| | | 19 | | /// Space complexity - O(n) |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="nums"></param> |
| | | 22 | | /// <returns></returns> |
| | | 23 | | public int NumIdenticalPairs(int[] nums) |
| | 4 | 24 | | { |
| | 4 | 25 | | var countDictionary = new Dictionary<int, int>(); |
| | | 26 | | |
| | 188 | 27 | | foreach (var num in nums) |
| | 88 | 28 | | { |
| | 88 | 29 | | if (!countDictionary.TryAdd(num, 1)) |
| | 71 | 30 | | { |
| | 71 | 31 | | countDictionary[num]++; |
| | 71 | 32 | | } |
| | 88 | 33 | | } |
| | | 34 | | |
| | 38 | 35 | | return countDictionary.Select(pair => pair.Value).Select(count => count * (count - 1) / 2).Sum(); |
| | 4 | 36 | | } |
| | | 37 | | } |