static public string Play(string input) { //初期値 var moveMng = new MovementManager('B', 'A'); var output = new StringBuilder(); output.Append('A'); foreach (var command in input) { if (command == 'r') { moveMng.TurnRight(); } else if (command == 'l') { moveMng.TurnLeft(); } else if (command == 'b') { moveMng.Back(); } else { return(string.Format("無効な文字\'{0}\'が含まれています", command)); } output.Append(moveMng.NowNode); } return(output.ToString()); }