private string GetMinPath()
{
var result = new StringBuilder();
long currentIndex = _toCity;
while (currentIndex != _fromCity)
{
DistancePath path = _distancePathByCityNumber[currentIndex];
result.Insert(0, $" {currentIndex + 1}");
currentIndex = path.BackCity;
}
result.Insert(0, (_fromCity + 1).ToString());
return(result.ToString());
}
public MinDistanceResult GetMinDistance()
{
if (_result != null)
{
return(_result);
}
_heap.Add(new CityDistance(_fromCity, _fromCity, 0));
while (!_minDistanceCities.Contains(_toCity))
{
CityDistance currentCity = _heap.Pop();
long currentCityIndex = currentCity.To;
if (currentCity == null)
{
return(MinDistanceResult.NotFound());
}
_minDistanceCities.Add(currentCityIndex);
var roadsFromCurrentCity = _distanceMap.GetRoadsFromCity(currentCityIndex);
foreach (var(toCity, distance) in roadsFromCurrentCity)
{
long newDistance = distance + currentCity.Distance;
long currentMinDistance = _distancePathByCityNumber.ContainsKey(toCity)
? _distancePathByCityNumber[toCity].Distance
: long.MaxValue;
if (newDistance < currentMinDistance)
{
_heap.Add(new CityDistance(currentCityIndex, toCity, newDistance));
_distancePathByCityNumber[toCity] = new DistancePath(newDistance, currentCityIndex);
}
}
}
_result = new MinDistanceResult(
_distancePathByCityNumber[_toCity].Distance,
GetMinPath());
return(_result);
}