| | | 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 | | using LeetCode.Core.Models; |
| | | 13 | | |
| | | 14 | | namespace LeetCode.Algorithms.RemoveNthNodeFromEndOfList; |
| | | 15 | | |
| | | 16 | | /// <inheritdoc /> |
| | | 17 | | public class RemoveNthNodeFromEndOfListTwoPointers : IRemoveNthNodeFromEndOfList |
| | | 18 | | { |
| | | 19 | | /// <summary> |
| | | 20 | | /// Time complexity - O(n), where n is the number of nodes in the linked list |
| | | 21 | | /// Space complexity - O(1) |
| | | 22 | | /// </summary> |
| | | 23 | | /// <param name="head"></param> |
| | | 24 | | /// <param name="n"></param> |
| | | 25 | | /// <returns></returns> |
| | | 26 | | public ListNode? RemoveNthFromEnd(ListNode? head, int n) |
| | 4 | 27 | | { |
| | 4 | 28 | | var dummyHead = new ListNode { next = head }; |
| | | 29 | | |
| | 4 | 30 | | var slowPointer = dummyHead; |
| | 4 | 31 | | var fastPointer = dummyHead; |
| | | 32 | | |
| | 28 | 33 | | for (var i = 0; i <= n; i++) |
| | 10 | 34 | | { |
| | 10 | 35 | | fastPointer = fastPointer?.next; |
| | 10 | 36 | | } |
| | | 37 | | |
| | 8 | 38 | | while (fastPointer != null) |
| | 4 | 39 | | { |
| | 4 | 40 | | slowPointer = slowPointer?.next; |
| | 4 | 41 | | fastPointer = fastPointer.next; |
| | 4 | 42 | | } |
| | | 43 | | |
| | 4 | 44 | | if (slowPointer != null) |
| | 4 | 45 | | { |
| | 4 | 46 | | slowPointer.next = slowPointer.next?.next; |
| | 4 | 47 | | } |
| | | 48 | | |
| | 4 | 49 | | return dummyHead.next; |
| | 4 | 50 | | } |
| | | 51 | | } |