| | | 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 | | using System.Text; |
| | | 13 | | |
| | | 14 | | namespace LeetCode.Algorithms.MultiplyStrings; |
| | | 15 | | |
| | | 16 | | /// <inheritdoc /> |
| | | 17 | | public sealed class MultiplyStringsStack : IMultiplyStrings |
| | | 18 | | { |
| | | 19 | | /// <summary> |
| | | 20 | | /// Time complexity - O(n * m) |
| | | 21 | | /// Space complexity - O(n + m) |
| | | 22 | | /// </summary> |
| | | 23 | | /// <param name="num1"></param> |
| | | 24 | | /// <param name="num2"></param> |
| | | 25 | | /// <returns></returns> |
| | | 26 | | public string Multiply(string num1, string num2) |
| | 5 | 27 | | { |
| | 5 | 28 | | if (num1 == "0" || num2 == "0") |
| | 1 | 29 | | { |
| | 1 | 30 | | return "0"; |
| | | 31 | | } |
| | | 32 | | |
| | 4 | 33 | | var valuesStack = new Stack<string>(); |
| | | 34 | | |
| | 4 | 35 | | var num2Index = num2.Length - 1; |
| | | 36 | | |
| | 4 | 37 | | var num2Multiplier = 0; |
| | | 38 | | |
| | 17 | 39 | | while (num2Index >= 0) |
| | 13 | 40 | | { |
| | 13 | 41 | | var multiplyValuesStack = new Stack<int>(); |
| | | 42 | | |
| | 13 | 43 | | var num2Value = (int)char.GetNumericValue(num2[num2Index]); |
| | | 44 | | |
| | 13 | 45 | | num2Index--; |
| | | 46 | | |
| | 13 | 47 | | var num1Index = num1.Length - 1; |
| | | 48 | | |
| | 13 | 49 | | var remainder = 0; |
| | | 50 | | |
| | 50 | 51 | | while (num1Index >= 0) |
| | 37 | 52 | | { |
| | 37 | 53 | | var num1Value = (int)char.GetNumericValue(num1[num1Index]); |
| | | 54 | | |
| | 37 | 55 | | num1Index--; |
| | | 56 | | |
| | 37 | 57 | | var value = (num1Value * num2Value) + remainder; |
| | 37 | 58 | | remainder = value / 10; |
| | 37 | 59 | | value = value % 10; |
| | | 60 | | |
| | 37 | 61 | | multiplyValuesStack.Push(value); |
| | 37 | 62 | | } |
| | | 63 | | |
| | 13 | 64 | | if (remainder > 0) |
| | 9 | 65 | | { |
| | 9 | 66 | | multiplyValuesStack.Push(remainder); |
| | 9 | 67 | | } |
| | | 68 | | |
| | 13 | 69 | | var valueStringBuilder = new StringBuilder(); |
| | | 70 | | |
| | 59 | 71 | | while (multiplyValuesStack.Count > 0) |
| | 46 | 72 | | { |
| | 46 | 73 | | var value = multiplyValuesStack.Pop(); |
| | | 74 | | |
| | 46 | 75 | | valueStringBuilder.Append(value); |
| | 46 | 76 | | } |
| | | 77 | | |
| | 68 | 78 | | for (var i = 0; i < num2Multiplier; i++) |
| | 21 | 79 | | { |
| | 21 | 80 | | valueStringBuilder.Append('0'); |
| | 21 | 81 | | } |
| | | 82 | | |
| | 13 | 83 | | valuesStack.Push(valueStringBuilder.ToString()); |
| | | 84 | | |
| | 13 | 85 | | num2Multiplier++; |
| | 13 | 86 | | } |
| | | 87 | | |
| | 4 | 88 | | var result = valuesStack.Pop(); |
| | | 89 | | |
| | 13 | 90 | | while (valuesStack.Count > 0) |
| | 9 | 91 | | { |
| | 9 | 92 | | var value = valuesStack.Pop(); |
| | | 93 | | |
| | 9 | 94 | | result = Add(result, value); |
| | 9 | 95 | | } |
| | | 96 | | |
| | 4 | 97 | | return result; |
| | 5 | 98 | | } |
| | | 99 | | |
| | | 100 | | private static string Add(string num1, string num2) |
| | 9 | 101 | | { |
| | 9 | 102 | | var num1Index = num1.Length - 1; |
| | 9 | 103 | | var num2Index = num2.Length - 1; |
| | | 104 | | |
| | 9 | 105 | | var remainder = 0; |
| | 9 | 106 | | var valuesStack = new Stack<int>(); |
| | | 107 | | |
| | 76 | 108 | | while (num1Index >= 0 || num2Index >= 0) |
| | 67 | 109 | | { |
| | 67 | 110 | | var num1Value = num1Index >= 0 ? (int)char.GetNumericValue(num1[num1Index--]) : 0; |
| | 67 | 111 | | var num2Value = num2Index >= 0 ? (int)char.GetNumericValue(num2[num2Index--]) : 0; |
| | | 112 | | |
| | 67 | 113 | | var sum = num1Value + num2Value + remainder; |
| | | 114 | | |
| | 67 | 115 | | remainder = sum / 10; |
| | | 116 | | |
| | 67 | 117 | | valuesStack.Push(sum % 10); |
| | 67 | 118 | | } |
| | | 119 | | |
| | 9 | 120 | | if (remainder > 0) |
| | 0 | 121 | | { |
| | 0 | 122 | | valuesStack.Push(remainder); |
| | 0 | 123 | | } |
| | | 124 | | |
| | 9 | 125 | | var resultStringBuilder = new StringBuilder(); |
| | | 126 | | |
| | 76 | 127 | | while (valuesStack.Count > 0) |
| | 67 | 128 | | { |
| | 67 | 129 | | var value = valuesStack.Pop(); |
| | | 130 | | |
| | 67 | 131 | | resultStringBuilder.Append(value); |
| | 67 | 132 | | } |
| | | 133 | | |
| | 9 | 134 | | return resultStringBuilder.ToString(); |
| | 9 | 135 | | } |
| | | 136 | | } |