/// <summary>
/// Returns least resistance path.
/// </summary>
/// <param name="inputFilePath">Input File Path</param>
/// <returns>PathResult</returns>
public PathResult Find(string inputFilePath)
{
PathResult result = new PathResult();
try
{
ReturnResult getDataTableResult = new ReturnResult();
DataTable dataGrid = new DataTable();
getDataTableResult = Common.GetDataTableFromInputFile(inputFilePath);
dataGrid = (DataTable)getDataTableResult.ReturnValue;
if (!getDataTableResult.HasErrors)
{
if (dataGrid.Rows.Count == 0)
{
result.Success = false;
result.Resistance = 0;
result.LeastPath = "";
}
// Loop through each row and all possible paths to get the lease path
for (int iCount = 1; iCount <= dataGrid.Rows.Count; iCount++)
{
PathResult rowLeast = FindRecursion(dataGrid, 0, "", iCount, 1);
if (result.Resistance == int.MinValue || rowLeast.Resistance < result.Resistance)
{
result = rowLeast;
}
}
}
else
{
// No need to write error to log file as we had already done it inside Common.GetDataTableFromInputFile function
result.HasErrors = true;
result.ErrorMessage = getDataTableResult.ErrorMessage;
}
}
catch (Exception ex)
{
Common.WriteLog(ex.Message);
result.HasErrors = true;
result.ErrorMessage = ex.Message;
}
return(result);
}
/// <summary>
/// Find and calculate resistance through all possible paths.
/// </summary>
/// <param name="dataGrid">DataTable contains grid data</param>
/// <param name="oldResistance">Old resistance value</param>
/// <param name="oldPath">Old least Path</param>
/// <param name="row">Current row position</param>
/// <param name="column">Current column position</param>
/// <returns>PathResult</returns>
private PathResult FindRecursion(DataTable dataGrid, int?oldResistance, string oldPath, int row, int column)
{
PathResult result = new PathResult();
try {
if (dataGrid != null && dataGrid.Rows.Count >= row && dataGrid.Columns.Count >= column)
{
// Append current value to the previous path.
int? resistance = oldResistance + GetResistence(dataGrid, row, column);
string path = String.Format("{0} {1}", oldPath, row).Trim();
// Stop recurssion if resistance > 50
if (resistance > 50)
{
result.Success = false;
result.Resistance = oldResistance;
result.LeastPath = oldPath;
return(result);
}
else if (column == dataGrid.Columns.Count) // Stop continuing recursion as we had already reached to the last column
{
result.Success = true;
result.Resistance = resistance;
result.LeastPath = path;
return(result);
}
// Loop through all possible paths..
Coordinates upPair = GetUpCoordinates(dataGrid, row, column);
Coordinates straightPair = GetStraightCoordinates(dataGrid, row, column);
Coordinates downPair = GetDownCoordinates(dataGrid, row, column);
PathResult up = FindRecursion(dataGrid, resistance, path, upPair.row, upPair.column);
PathResult straight = FindRecursion(dataGrid, resistance, path, straightPair.row, straightPair.column);
PathResult down = FindRecursion(dataGrid, resistance, path, downPair.row, downPair.column);
// Validate and return least path.
if (up.Resistance < straight.Resistance && up.Resistance < down.Resistance)
{
return(up);
}
else if (straight.Resistance < down.Resistance)
{
return(straight);
}
else
{
return(down);
}
}
else
{
string message = "File does not exist or not accessible.";
Common.WriteLog(message);
result.HasErrors = true;
result.ErrorMessage = message;
}
}catch (Exception ex)
{
Common.WriteLog(ex.Message);
result.HasErrors = true;
result.ErrorMessage = ex.Message;
}
return(result);
}