日常生活中，上班下班坐地鐵已經是常事，每當我想去某一個遠一點的地方，如果有地鐵首選就是地鐵，因為方便嘛！每次坐地鐵，我們都是憑肉眼去得出我們心中最佳的換乘方案，但是，如果對於線路較少的城市來說，這個方法是最快的，但是如果對於線路較多的城市，例如北京或者上海，十幾條線路交叉穿梭，我們可能看到都暈了，怎 ...
日常生活中，上班下班坐地鐵已經是常事，每當我想去某一個遠一點的地方，如果有地鐵首選就是地鐵，因為方便嘛！每次坐地鐵，我們都是憑肉眼去得出我們心中最佳的換乘方案，但是，如果對於線路較少的城市來說，這個方法是最快的，但是如果對於線路較多的城市，例如北京或者上海，十幾條線路交叉穿梭，我們可能看到都暈了，怎麼坐才是時間最短路程最短的，我們要算出來不是不可以但是很麻煩，我們也可以想一想，百度地圖的地鐵換乘演算法是怎麼實現的，於是，閑著沒事，我就想寫一個通用的地鐵換乘查詢程式，想用電腦運算得出科學一點的換乘方案供自己參考，假設先不考慮站點間的距離差異，我們以乘坐站點數最少為最優方案，依照這個條件去編碼實現查找的演算法，其實也沒用上什麼高大上的演算法，因為也不會哈哈，話不多說，先上效果圖：
有對應城市的線路圖：
站點智能提示：
項目結構圖：
我的開發思路：
1、採用xml存儲站點數據，如下：
2、代碼中使用集合初始化線路數據
1 /// <summary> 2 /// 初始化地鐵線路數據 3 /// </summary> 4 /// <param name="city">城市</param> 5 public static void InitSubwayLine(CityEnum city) 6 { 7 if (AllSubwayLines != null && AllSubwayLines.Any() && _currentCity == city) return; 8 _currentCity = city; 9 var xmlName = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "xml/" + city.ToString() + ".xml"); 10 _doc = XDocument.Load(xmlName); 11 AllSubwayLines = _doc.Root.Elements().Select(x => 12 { 13 var line = new SubwayLine 14 { 15 No = x.Attribute("No").Value, 16 Name = x.Attribute("Name").Value, 17 IsRound = x.Attribute("IsRound") == null ? false : bool.Parse(x.Attribute("IsRound").Value), 18 Stations = x.Elements().Select((y, i) => new Station 19 { 20 Index = i, 21 Name = y.Attribute("Name").Value, 22 LineNo = x.Attribute("No").Value, 23 CanTransfer = y.Attribute("CanTransfer") == null ? false : bool.Parse(y.Attribute("CanTransfer").Value), 24 TransferNo = y.Attribute("TransferNo") == null ? null : y.Attribute("TransferNo").Value 25 }).ToList() 26 }; 27 var translines = line.GetTransStations().Select(z => z.TransferNo.Split(',')).ToList(); 28 foreach (var transline in translines) 29 { 30 foreach (var li in transline) 31 { 32 line.TransferLines.Add(li); 33 } 34 } 35 line.TransferLines = line.TransferLines.Distinct().ToList(); 36 return line; 37 }).ToList(); 38 }
3、分多種情況進行處理，核心代碼（代碼有點長，我也在想方法濃縮代碼，還望各位看官耐心(┬＿┬)）：
1 /// <summary> 2 /// 獲取地鐵乘車信息 3 /// </summary> 4 /// <param name="depStation">出發站</param> 5 /// <param name="destStation">到達站</param> 6 /// <param name="city">所在城市</param> 7 /// <returns>返回各種換乘方案</returns> 8 public static List<QueryResult> GetRideSubwayInfo(string depStation, string destStation, CityEnum city) 9 { 10 InitSubwayLine(city); 11 if (string.IsNullOrWhiteSpace(depStation) || string.IsNullOrWhiteSpace(destStation) 12 || !AllSubwayLines.Exists(x => x.Stations.Exists(y => y.Name.Equals(depStation))) 13 || !AllSubwayLines.Exists(x => x.Stations.Exists(y => y.Name.Equals(destStation)))) 14 return null;//出發站或到達站線上路上不存在！ 15 16 //各種換乘提示 17 //同一條線路 18 var msg_oneline = "在{0}【{1}】上車，經過{2}站到達目的站【{3}】。\r\n具體線路為：\r\n(出發){4}(到達)\r\n總搭乘站點數：{5}\r\n"; 19 //換乘1次 20 var msg_transOnce = "在{0}【{1}】上車，經過{2}站在【{3}】下車，換乘{4}，經過{5}站到達目的站【{6}】。\r\n具體線路為：\r\n(出發){7}(此處換乘{4})-->{8}(到達)\r\n總搭乘站點數：{9}\r\n"; 21 //換乘2次 22 var msg_transTwice = "在{0}【{1}】上車，經過{2}站在【{3}】下車，換乘{4}，經過{5}站在【{6}】下車，換乘{7}，經過{8}站到達目的站【{9}】。\r\n具體線路為：\r\n(出發){10}(此處換乘{4})-->{11}(此處換乘{7})-->{12}(到達)\r\n總搭乘站點數：{13}\r\n"; 23 //換乘3次 24 var msg_transThreetimes = "在{0}【{1}】上車，經過{2}站在【{3}】下車，換乘{4}，經過{5}站在【{6}】下車，換乘{7}，經過{8}站在【{9}】下車，換乘{10}，經過{11}站到達目的站【{12}】。" 25 + "\r\n具體線路為：\r\n(出發){13}(此處換乘{4})-->{14}(此處換乘{7})-->{15}(此處換乘{10})-->{16}(到達)\r\n總搭乘站點數：{17}\r\n"; 26 //換乘4次 27 var msg_transFourtimes = "在{0}【{1}】上車，經過{2}站在【{3}】下車，換乘{4}，經過{5}站在【{6}】下車，換乘{7}，經過{8}站在【{9}】下車，換乘{10}，經過{11}站在【{12}】下車，換乘{13}，經過{14}站到達目的站【{15}】。" 28 + "\r\n具體線路為：\r\n(出發){16}(此處換乘{4})-->{17}(此處換乘{7})-->{18}(此處換乘{10})-->{19}(此處換乘{13})-->{20}(到達)\r\n總搭乘站點數：{21}\r\n"; 29 30 //保存各種換乘方案 31 var result = new List<QueryResult>(); 32 //第一步：先查找始發站和到達站在哪一條線路 33 var afterDepLines = GetAcrossLines(depStation); 34 var afterDestLines = GetAcrossLines(destStation); 35 //根據同一條線和不同線路展開分析 36 if (IsSameLine(depStation, destStation)) 37 { 38 #region 同一條線路 39 var commLines = afterDepLines.Where(x => afterDestLines.Select(y => y.No).Contains(x.No)).ToList(); 40 //判斷線路是否相同，相同直接計算站點距離 41 var depIndex = GetIndexOnLine(depStation, commLines.First()); 42 var destIndex = GetIndexOnLine(destStation, commLines.First()); 43 var crossStations = commLines.First().Stations.Between(depIndex, destIndex).Select(x => x.Name).ToList(); 44 var range = crossStations.Count - 1; 45 if (depIndex > destIndex) crossStations.Reverse(); 46 var rs = msg_oneline.FormatTo(commLines.First().ToString(), depStation, range, destStation, 47 crossStations.ToJoinString(), range); 48 result.Add(new QueryResult() { Description = rs, Range = range }); 49 #endregion 50 } 51 else 52 { 53 #region 不同線路 54 if (!IsTransferStation(depStation) && !IsTransferStation(destStation))//如果始發站和終點站都不是換乘站，則表示始發站和到達站都是只有一條線路通過 55 { 56 if (afterDepLines.First().IsIntersect(afterDestLines.First())) 57 { 58 #region 如果兩條線路交叉，一定有換乘站點 59 var clist = GetAcrossStations(afterDepLines.First(), afterDestLines.First()).Select(x => x.Name).ToList(); 60 var i = GetIndexOnLine(depStation, afterDepLines.First()); 61 var j = GetIndexOnLine(clist.First(), afterDepLines.First()); 62 var k = GetIndexOnLine(destStation, afterDestLines.First()); 63 var l = GetIndexOnLine(clist.First(), afterDestLines.First()); 64 var coss1 = afterDepLines.First().Stations.Between(i, j).Select(x => x.Name).ToList(); 65 var coss2 = afterDestLines.First().Stations.Between(k, l).Select(x => x.Name).ToList(); 66 if (i > j) coss1.Reverse(); 67 if (k < l) coss2.Reverse(); 68 var rang1 = coss1.Count - 1; 69 var rang2 = coss2.Count - 1; 70 var h = rang1 + rang2; //站點數 71 var rs = msg_transOnce.FormatTo(afterDepLines.First().ToString(), depStation, rang1, clist.First(), 72 afterDestLines.First().ToString(), rang2, destStation, 73 coss1.ToJoinString(), coss2.Where(x => x != clist.First()).ToJoinString(), h); 74 result.Add(new QueryResult() 75 { 76 Description = rs, 77 Range = h, 78 TransferStations = new List<string>() { clist.First() }, 79 TransferTimes = 1 80 }); 81 #endregion 82 } 83 else 84 { 85 #region 不交叉，需要通過第三條線路換乘，即多次換乘 86 var depSta = GetStation(depStation); 87 var destSta = GetStation(destStation); 88 //找出兩條線路的可換乘站點，找出可換乘相同線路的站點 89 var trans1 = afterDepLines.First().GetTransStations(); 90 var trans2 = afterDestLines.First().GetTransStations(); 91 var trans3 = new List<Station>(); 92 var trans4 = new List<Station>(); 93 var expets = trans1.Join(trans2, x => x.TransferNo, y => y.TransferNo, (x, y) => 94 { 95 trans3.Add(x); 96 trans4.Add(y); 97 return x.Name + "---" + y.Name; 98 }).ToList(); 99 if (expets.Any()) 100 { 101 #region 兩次換乘 102 //trans3.Count和trans4.Count必定相等 103 //計算最短距離，列出所有換乘方案 104 for (var i = 0; i < trans3.Count; i++) 105 { 106 var tranLine = GetLine(trans3[i].TransferNo); 107 //獲取這兩個站點在此線路的索引 108 var ix1 = depSta.Index; 109 var ix2 = destSta.Index; 110 var iix1 = GetIndexOnLine(trans3[i].Name, depSta.LineNo); 111 var iix2 = GetIndexOnLine(trans4[i].Name, destSta.LineNo); 112 var tx1 = GetIndexOnLine(trans3[i].Name, tranLine); 113 var tx2 = GetIndexOnLine(trans4[i].Name, tranLine); 114 115 var depRange = afterDepLines.First().Stations.Between(ix1, iix1).Select(x => x.Name).ToList(); 116 var destRange = afterDestLines.First().Stations.Between(ix2, iix2).Select(x => x.Name).ToList(); 117 var transRange = tranLine.Stations.Between(tx1, tx2).Select(x => x.Name).ToList(); 118 if (ix1 > iix1) depRange.Reverse(); 119 if (ix2 < iix2) destRange.Reverse(); 120 if (tx1 > tx2) transRange.Reverse(); 121 var r1 = depRange.Count - 1; 122 var r2 = destRange.Count - 1; 123 var r3 = transRange.Count - 1; 124 var r = r1 + r2 + r3; 125 var rs = msg_transTwice.FormatTo(afterDepLines.First().ToString(), depStation, r1, 126 trans3[i].Name, 127 tranLine.ToString(), r3, trans4[i].Name, afterDestLines.First().ToString(), r2, 128 destStation, depRange.ToJoinString(), 129 transRange.Where(x => !x.IsSame(trans3[i].Name) && !x.IsSame(trans4[i].Name)).ToJoinString(), 130 destRange.ToJoinString(), r); 131 result.Add(new QueryResult() 132 { 133 Description = rs, 134 Range = r, 135 TransferTimes = 2, 136 TransferStations = new List<string>() { trans3[i].Name, trans4[i].Name } 137 }); 138 } 139 #endregion 140 } 141 #region 查找3次以上換乘的可能結果，尋求最短距離 142 var trlines1 = afterDepLines.First().TransferLines.Select(GetLine).ToList(); 143 var trlines2 = afterDestLines.First().TransferLines.Select(GetLine).ToList(); 144 var destss = new List<Station>(); 145 146 #region 換乘3次 147 foreach (var depline in trlines1) 148 { 149 foreach (var destline in trlines2) 150 { 151 var ss = destline.GetAcrossStations(depline); 152 if (!ss.Any()) continue; //3次換乘 153 var slist1 = afterDepLines.First().GetAcrossStations(depline); 154 if (!slist1.Any()) continue; 155 var s1 = slist1.GetClosestStation(depSta.Name); 156 var s1_ix1 = depSta.Index; 157 var s1_ix2 = s1.Index; 158 var s1_range = 159 afterDepLines.First() 160 .Stations.Between(s1_ix1, s1_ix2) 161 .Select(x => x.Name) 162 .ToList(); 163 var s1_h = s1_range.Count - 1; 164 if (s1_ix1 > s1_ix2) s1_range.Reverse(); 165 166 var s2_ix1 = GetIndexOnLine(s1.Name, depline); 167 var s2_ix2 = GetIndexOnLine(ss.First().Name, depline); 168 var s2_range = depline.Stations.Between(s2_ix1, s2_ix2).Select(x => x.Name).ToList(); 169 var s2_h = s2_range.Count - 1; 170 if (s2_ix1 > s2_ix2) s2_range.Reverse(); 171 172 var slist3 = destline.GetAcrossStations(afterDestLines.First()); 173 if (!slist3.Any()) continue; 174 var s3 = slist3.GetClosestStation(ss.First().Name); 175 var s3_ix1 = s3.Index; 176 var s3_ix2 = ss.First().Index; 177 var s3_range = destline.Stations.Between(s3_ix1, s3_ix2).Select(x => x.Name).ToList(); 178 var s3_h = s3_range.Count - 1; 179 if (s3_ix1 < s3_ix2) s3_range.Reverse(); 180 181 var s4_ix1 = GetIndexOnLine(s3.Name, afterDestLines.First()); 182 var s4_ix2 = destSta.Index; 183 var s4_range = 184 afterDestLines.First() 185 .Stations.Between(s4_ix1, s4_ix2) 186 .Select(x => x.Name) 187 .ToList(); 188 var s4_h = s4_range.Count - 1; 189 if (s4_ix1 > s4_ix2) s4_range.Reverse(); 190 191 var h = s1_h + s2_h + s3_h + s4_h; 192 var rs = msg_transThreetimes.FormatTo(afterDepLines.First().ToString(), depStation, 193 s1_h, s1.Name, 194 depline.ToString(), s2_h, ss.First().Name, 195 GetLine(ss.First().LineNo).ToString(), s3_h, s3.Name, 196 afterDestLines.First().ToString(), s4_h, destStation, s1_range.ToJoinString(), 197 s2_range.Where(x => x != s1.Name).ToJoinString(), 198 s3_range.Where(x => x != ss.First().Name).ToJoinString(), 199 s4_range.Where(x => x != s3.Name).ToJoinString(), h); 200 result.Add(new QueryResult() 201 { 202 Description = rs, 203 Range = h, 204 TransferTimes = 3, 205 TransferStations = 206 new List<string>() 207 { 208 s1.Name, 209 ss.First().Name, 210 s3.Name 211 } 212 }); 213 destss.AddRange(ss); 214 } 215 } 216 #endregion 217 218 if (!destss.Any()) //換乘4次 219 { 220 #region 換乘4次 221 foreach (var depline in trlines1) 222 { 223 foreach (var destline in trlines2) 224 { 225 var deptrlines = 226 depline.TransferLines.Where(x => x != afterDepLines.First().No) 227 .Select(GetLine) 228 .ToList(); 229 foreach (var line in deptrlines) 230 { 231 var s1 = line.GetAcrossStations(destline); 232 if (!s1.Any()) continue; //4次換乘 233 var trlist1 = afterDepLines.First().GetAcrossStations(depline); 234 if (!trlist1.Any()) continue; 235 var tr1 = trlist1.GetClosestStation(depSta.Name); 236 var s1_ix1 = depSta.Index; 237 var s1_ix2 = tr1.Index; 238 var s1_range = 239 afterDepLines.First() 240 .Stations.Between(s1_ix1, s1_ix2) 241 .Select(x => x.Name) 242 .ToList(); 243 var h1 = s1_range.Count - 1; 244 if (s1_ix1 > s1_ix2) s1_range.Reverse(); 245 246 var trlist2 = GetLine(tr1.TransferNo).GetAcrossStations(line); 247 if (!trlist2.Any()) continue; 248 var tr2 = trlist2.GetClosestStation(tr1.Name); 249 var s2_ix1 = GetIndexOnLine(tr1.Name, depline); 250 var s2_ix2 = tr2.Index; 251 var s2_range = 252 depline.Stations.Between(s2_ix1, s2_ix2) 253 .Select(x => x.Name) 254 .ToList(); 255 var h2 = s2_range.Count - 1; 256 if (s2_ix1 > s2_ix2) s2_range.Reverse(); 257 258 var s3_ix1 = GetIndexOnLine(tr2.Name, line); 259 var s3_ix2 = s1.First().Index; 260 var s3_range = 261 line.Stations.Between(s3_ix1, s3_ix2) 262 .Select(x => x.Name) 263 .ToList(); 264 var h3 = s3_range.Count - 1; 265 if (s3_ix1 > s3_ix2) s3_range.Reverse(); 266 267 var trlist3 = destline.GetAcrossStations(afterDestLines.First()); 268 if (!trlist3.Any()) continue; 269 var tr3 = trlist3.GetClosestStation(s1.First().Name); 270 var s4_ix1 = GetIndexOnLine(s1.First().Name, destline); 271 var s4_ix2 = tr3.Index; 272 var s4_range = 273 destline.Stations.Between(s4_ix1, s4_ix2) 274 .Select(x => x.Name) 275 .ToList(); 276 var h4 = s4_range.Count - 1; 277 if (s4_ix1 > s4_ix2) s4_range.Reverse(); 278 279 var s5_ix1 = GetIndexOnLine(tr3.Name, afterDestLines.First()); 280 var s5_ix2 = destSta.Index; 281 var s5_range = 282 afterDestLines.First() 283 .Stations.Between(s5_ix1, s5_ix2) 284 .Select(x => x.Name) 285 .ToList(); 286 var h5 = s5_range.Count - 1; 287 if (s5_ix1 > s5_ix2) s5_range.Reverse(); 288 var h = h1 + h2 + h3 + h4 + h5; 289 var rs = 290 msg_transFourtimes.FormatTo(afterDepLines.First().ToString(), 291 depStation, h1, tr1.Name, 292 depline.ToString(), h2, tr2.Name, 293 line.ToString(), h3, s1.First().Name, 294 destline.ToString(), h4, tr3.Name, 295 afterDestLines.First().ToString(), h5, destStation, 296 s1_range.ToJoinString(), 297 s2_range.Where(x => x != tr1.Name).ToJoinString(), 298 s3_range.Where(x => x != tr2.Name).ToJoinString(), 299 s4_range.Where(x => x != tr2.Name && x != s1.First().Name).ToJoinString(), 300 s5_range.Where(x => x != tr3.Name).ToJoinString(), h); 301 result.Add(new QueryResult() 302 { 303 Description = rs, 304 Range = h, 305 TransferTimes = 4, 306 TransferStations = 307 new List<string>() 308 { 309 tr1.Name, 310 tr2.Name, 311 s1.First().Name, 312 tr3.Name 313 } 314 }); 315 destss.AddRange(s1); 316 } 317 } 318 } 319 #endregion 320 } 321 if (!destss.Any())//換乘4次以上 322 { 323 324 } 325 #endregion 326 #endregion 327 } 328 } 329 else //始發站和到達站有其中一個是換乘站 330 { 331 //找出到達站經過的路線和始發站所在路線的交叉線路 332 var crossLines = GetAcrossLines(depStation, destStation);
