| | | 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.RangeSumQueryMutable; |
| | | 13 | | |
| | | 14 | | /// <inheritdoc /> |
| | | 15 | | public class RangeSumQueryMutablePrefixSum : IRangeSumQueryMutable |
| | | 16 | | { |
| | | 17 | | private readonly int[] _nums; |
| | | 18 | | private readonly int[] _prefixSum; |
| | | 19 | | |
| | | 20 | | /// <summary> |
| | | 21 | | /// Time complexity - O(n) |
| | | 22 | | /// Space complexity - O(n) |
| | | 23 | | /// </summary> |
| | | 24 | | /// <param name="nums"></param> |
| | 1 | 25 | | public RangeSumQueryMutablePrefixSum(int[] nums) |
| | 1 | 26 | | { |
| | 1 | 27 | | _nums = nums; |
| | | 28 | | |
| | 1 | 29 | | _prefixSum = new int[nums.Length + 1]; |
| | | 30 | | |
| | 8 | 31 | | for (var i = 0; i < nums.Length; i++) |
| | 3 | 32 | | { |
| | 3 | 33 | | _prefixSum[i + 1] = _prefixSum[i] + nums[i]; |
| | 3 | 34 | | } |
| | 1 | 35 | | } |
| | | 36 | | |
| | | 37 | | /// <summary> |
| | | 38 | | /// Time complexity - O(n) |
| | | 39 | | /// Space complexity - O(1) |
| | | 40 | | /// </summary> |
| | | 41 | | /// <param name="index"></param> |
| | | 42 | | /// <param name="val"></param> |
| | | 43 | | public void Update(int index, int val) |
| | 1 | 44 | | { |
| | 1 | 45 | | _nums[index] = val; |
| | | 46 | | |
| | 6 | 47 | | for (var i = index; i < _nums.Length; i++) |
| | 2 | 48 | | { |
| | 2 | 49 | | _prefixSum[i + 1] = _prefixSum[i] + _nums[i]; |
| | 2 | 50 | | } |
| | 1 | 51 | | } |
| | | 52 | | |
| | | 53 | | /// <summary> |
| | | 54 | | /// Time complexity - O(1) |
| | | 55 | | /// Space complexity - O(1) |
| | | 56 | | /// </summary> |
| | | 57 | | /// <param name="left"></param> |
| | | 58 | | /// <param name="right"></param> |
| | | 59 | | /// <returns></returns> |
| | | 60 | | public int SumRange(int left, int right) |
| | 2 | 61 | | { |
| | 2 | 62 | | return _prefixSum[right + 1] - _prefixSum[left]; |
| | 2 | 63 | | } |
| | | 64 | | } |