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| 1 | +using System; |
| 2 | +using System.Collections.Generic; |
| 3 | + |
| 4 | +public class Solution |
| 5 | +{ |
| 6 | + public static void Main(string[] args) |
| 7 | + { |
| 8 | + Console.WriteLine(MinWindow("ADOBECODEBANC", "ABC")); |
| 9 | + Console.WriteLine(MinWindow2("ADOBECODEBANC", "ABC")); |
| 10 | + |
| 11 | + Console.ReadKey(); |
| 12 | + } |
| 13 | + |
| 14 | + #region Approach 1 (Brute Force) |
| 15 | + private static bool _IsSubstringIncludingText(string substring, string text) |
| 16 | + { |
| 17 | + if (string.IsNullOrWhiteSpace(substring) || |
| 18 | + string.IsNullOrWhiteSpace(text) || |
| 19 | + (substring.Length < text.Length)) |
| 20 | + { |
| 21 | + return false; |
| 22 | + } |
| 23 | + |
| 24 | + for (int i = 0; i < text.Length; i++) |
| 25 | + { |
| 26 | + if (!substring.Contains(text[i].ToString())) |
| 27 | + { |
| 28 | + return false; |
| 29 | + } |
| 30 | + |
| 31 | + int indexToDelete = substring.IndexOf(text[i]); |
| 32 | + substring = substring.Remove(indexToDelete, 1); |
| 33 | + } |
| 34 | + |
| 35 | + return true; |
| 36 | + } |
| 37 | + |
| 38 | + public static string MinWindow(string s, string t) |
| 39 | + { |
| 40 | + if (string.IsNullOrWhiteSpace(s) || string.IsNullOrWhiteSpace(t) || (s.Length < t.Length)) |
| 41 | + { |
| 42 | + return ""; |
| 43 | + } |
| 44 | + |
| 45 | + int startLengthOfWindow = 0; |
| 46 | + int minEndLengthOfWindow = t.Length; |
| 47 | + string windowSubstring = ""; |
| 48 | + string result = s + t; |
| 49 | + bool takeNextLetter = true; |
| 50 | + |
| 51 | + for (int i = startLengthOfWindow; i < s.Length; i++) |
| 52 | + { |
| 53 | + if (takeNextLetter) |
| 54 | + { |
| 55 | + windowSubstring += s[i]; |
| 56 | + } |
| 57 | + |
| 58 | + if (windowSubstring.Length >= minEndLengthOfWindow) |
| 59 | + { |
| 60 | + if (_IsSubstringIncludingText(windowSubstring, t)) |
| 61 | + { |
| 62 | + result = (windowSubstring.Length < result.Length) ? windowSubstring : result; |
| 63 | + |
| 64 | + if (result.Length == minEndLengthOfWindow) |
| 65 | + { |
| 66 | + return result; |
| 67 | + } |
| 68 | + |
| 69 | + windowSubstring = windowSubstring.Substring(1); |
| 70 | + i--; |
| 71 | + takeNextLetter = false; |
| 72 | + } |
| 73 | + else |
| 74 | + { |
| 75 | + takeNextLetter = true; |
| 76 | + } |
| 77 | + } |
| 78 | + |
| 79 | + } |
| 80 | + |
| 81 | + return result == (s + t) ? "" : result; |
| 82 | + } |
| 83 | + #endregion |
| 84 | + |
| 85 | + #region Approach 2 |
| 86 | + public static string MinWindow2(string s, string t) |
| 87 | + { |
| 88 | + if (string.IsNullOrWhiteSpace(s) || string.IsNullOrWhiteSpace(t) || (s.Length < t.Length)) |
| 89 | + { |
| 90 | + return ""; |
| 91 | + } |
| 92 | + |
| 93 | + var countT = InitializeDictionary(t); |
| 94 | + var window = new Dictionary<char, int>(); |
| 95 | + int have = 0; |
| 96 | + int need = countT.Count; |
| 97 | + int left = 0; |
| 98 | + int[] result = new[] { -1, -1 }; |
| 99 | + int minLength = int.MaxValue; |
| 100 | + |
| 101 | + for (int right = 0; right < s.Length; right++) |
| 102 | + { |
| 103 | + char c = s[right]; |
| 104 | + AddCharToDictionary(c, window); |
| 105 | + |
| 106 | + if (countT.ContainsKey(c) && window[c] == countT[c]) |
| 107 | + { |
| 108 | + have++; |
| 109 | + } |
| 110 | + |
| 111 | + while (have == need) |
| 112 | + { |
| 113 | + int windowSize = right - left + 1; |
| 114 | + if (windowSize < minLength) |
| 115 | + { |
| 116 | + result = new[] { left, right }; |
| 117 | + minLength = windowSize; |
| 118 | + } |
| 119 | + |
| 120 | + AdjustWindow(s, left, window, countT, ref have); |
| 121 | + left++; |
| 122 | + } |
| 123 | + } |
| 124 | + |
| 125 | + return minLength == int.MaxValue |
| 126 | + ? string.Empty |
| 127 | + : s.Substring(result[0], result[1] - result[0] + 1); |
| 128 | + } |
| 129 | + |
| 130 | + private static void AddCharToDictionary(char character, Dictionary<char, int> dict) |
| 131 | + { |
| 132 | + if (dict.ContainsKey(character)) |
| 133 | + { |
| 134 | + dict[character]++; |
| 135 | + } |
| 136 | + else |
| 137 | + { |
| 138 | + dict.Add(character, 1); |
| 139 | + } |
| 140 | + } |
| 141 | + |
| 142 | + private static Dictionary<char, int> InitializeDictionary(string t) |
| 143 | + { |
| 144 | + var countT = new Dictionary<char, int>(); |
| 145 | + foreach (char c in t) |
| 146 | + { |
| 147 | + AddCharToDictionary(c, countT); |
| 148 | + } |
| 149 | + return countT; |
| 150 | + } |
| 151 | + |
| 152 | + // Function to adjust the sliding window |
| 153 | + private static void AdjustWindow(string s, int left, Dictionary<char, int> window, Dictionary<char, int> countT, ref int have) |
| 154 | + { |
| 155 | + window[s[left]]--; |
| 156 | + if (countT.ContainsKey(s[left]) && window[s[left]] < countT[s[left]]) |
| 157 | + { |
| 158 | + have--; |
| 159 | + } |
| 160 | + } |
| 161 | + #endregion |
| 162 | +} |
| 163 | + |
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