| | | 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.FirstUniqueEvenElement; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public sealed class FirstUniqueEvenElementFrequencyArray : IFirstUniqueEvenElement |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(n) |
| | | 19 | | /// Space complexity - O(1) |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="nums"></param> |
| | | 22 | | /// <returns></returns> |
| | | 23 | | public int FirstUniqueEven(int[] nums) |
| | 2 | 24 | | { |
| | 2 | 25 | | Span<int> frequencies = stackalloc int[101]; |
| | | 26 | | |
| | 20 | 27 | | for (var i = 0; i < nums.Length; i++) |
| | 8 | 28 | | { |
| | 8 | 29 | | var num = nums[i]; |
| | | 30 | | |
| | 8 | 31 | | if (num % 2 != 0) |
| | 2 | 32 | | { |
| | 2 | 33 | | continue; |
| | | 34 | | } |
| | | 35 | | |
| | 6 | 36 | | frequencies[num]++; |
| | 6 | 37 | | } |
| | | 38 | | |
| | 12 | 39 | | for (var i = 0; i < nums.Length; i++) |
| | 5 | 40 | | { |
| | 5 | 41 | | var num = nums[i]; |
| | | 42 | | |
| | 5 | 43 | | if (num % 2 != 0) |
| | 1 | 44 | | { |
| | 1 | 45 | | continue; |
| | | 46 | | } |
| | | 47 | | |
| | 4 | 48 | | if (frequencies[num] == 1) |
| | 1 | 49 | | { |
| | 1 | 50 | | return num; |
| | | 51 | | } |
| | 3 | 52 | | } |
| | | 53 | | |
| | 1 | 54 | | return -1; |
| | 2 | 55 | | } |
| | | 56 | | } |