| | | 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.FindThePivotInteger; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public class FindThePivotIntegerIterative : IFindThePivotInteger |
| | | 16 | | { |
| | | 17 | | /// <summary> |
| | | 18 | | /// Time complexity - O(n log n) |
| | | 19 | | /// Space complexity - O(1) |
| | | 20 | | /// </summary> |
| | | 21 | | /// <param name="n"></param> |
| | | 22 | | /// <returns></returns> |
| | | 23 | | public int PivotInteger(int n) |
| | 4 | 24 | | { |
| | 4 | 25 | | var left = 1; |
| | 4 | 26 | | var right = n; |
| | | 27 | | |
| | 12 | 28 | | while (left <= right) |
| | 10 | 29 | | { |
| | 10 | 30 | | var mid = left + ((right - left) / 2); |
| | 10 | 31 | | var leftSum = Sum(1, mid); |
| | 10 | 32 | | var rightSum = Sum(mid, n); |
| | | 33 | | |
| | 10 | 34 | | if (leftSum == rightSum) |
| | 2 | 35 | | { |
| | 2 | 36 | | return mid; |
| | | 37 | | } |
| | | 38 | | |
| | 8 | 39 | | if (leftSum < rightSum) |
| | 6 | 40 | | { |
| | 6 | 41 | | left = mid + 1; |
| | 6 | 42 | | } |
| | | 43 | | else |
| | 2 | 44 | | { |
| | 2 | 45 | | right = mid - 1; |
| | 2 | 46 | | } |
| | 8 | 47 | | } |
| | | 48 | | |
| | 2 | 49 | | return -1; |
| | 4 | 50 | | } |
| | | 51 | | |
| | | 52 | | private static int Sum(int left, int right) |
| | 20 | 53 | | { |
| | 20 | 54 | | var sum = 0; |
| | | 55 | | |
| | 214 | 56 | | for (var i = left; i <= right; i++) |
| | 87 | 57 | | { |
| | 87 | 58 | | sum += i; |
| | 87 | 59 | | } |
| | | 60 | | |
| | 20 | 61 | | return sum; |
| | 20 | 62 | | } |
| | | 63 | | } |