| | | 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.FindLuckyIntegerInAnArray; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public class FindLuckyIntegerInAnArrayFrequencyArray : IFindLuckyIntegerInAnArray |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(n) |
| | | 19 | | /// Space complexity - O(1) |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="arr"></param> |
| | | 22 | | /// <returns></returns> |
| | | 23 | | public int FindLucky(int[] arr) |
| | 3 | 24 | | { |
| | 3 | 25 | | var frequencyArray = new int[500]; |
| | | 26 | | |
| | 39 | 27 | | foreach (var number in arr) |
| | 15 | 28 | | { |
| | 15 | 29 | | frequencyArray[number - 1]++; |
| | 15 | 30 | | } |
| | | 31 | | |
| | 2996 | 32 | | for (var i = frequencyArray.Length - 1; i >= 0; i--) |
| | 1497 | 33 | | { |
| | 1497 | 34 | | if (i + 1 == frequencyArray[i]) |
| | 2 | 35 | | { |
| | 2 | 36 | | return i + 1; |
| | | 37 | | } |
| | 1495 | 38 | | } |
| | | 39 | | |
| | 1 | 40 | | return -1; |
| | 3 | 41 | | } |
| | | 42 | | } |