/** appends city to the route */
void Route::addCity(const City &city)
{
cities_.push_back(city);
citiesIds_.push_back(city.getId());
}
//it loads the distances and prevs arrays of the Graph object according to the source city
void Graph::dijkstra( int source )
{
//vector<int> distances(size); dynamicly allocated no need to deallocation
//priority_queue<int, vector<int>, minHeapComparator> tmpDistances;
bool firstIteration = true;
bool isDone = false;
this->prevs = new int[this->numVertices];
this->distances = new int[this->numVertices];
// the completed paths array is parallel with the distances array and it consists of 1's and 0's as flags
bool *completedPaths = new bool[this->numVertices];
for(int i = 0; i < this->numVertices; i++)
completedPaths[i] = false; //initialize all of them with 0's
completedPaths[source] = true; //the source to source path is considered as completed
//initialize the distances and prev. values of nodes
for(int i = 0; i < this->numVertices; i++)
{
prevs[i] = -1; // prev. is null
this->distances[i] = 9999; //distance is infinite
(i == source) && ( this->distances[i] = 0); //initialize the source's distance with 0
}
//debugging
this->printCurrDistAndPrevs();
while(!isDone)
{
//for each iteration of the loop, determine the initial minIndex value
//initial minIndex is the first index with an uncompleted path
int minIndex;
//in the first iteration, do relaxation with the source node
if( firstIteration)
{
minIndex = source;
firstIteration = false;
}
else
{
for(int i = 0; i < numVertices; i++ )
{
if( !completedPaths[i])
{
minIndex = i;
break;
}
}
//now starting from the initial minIndex, search for real min. index
for(int i = 0; i < numVertices; i++)
{
//if that path is completed, just ignore
if( completedPaths[i] )
continue;
if( this->distances[i] < this->distances[minIndex] )
minIndex = i; // we have a new min. distance
}
}
//according to the Dijkstra's algorithm, the chosen one with min. distance is a completed path from now on.
completedPaths[minIndex] = true;
City *tmpCity = this->adjList[minIndex];
for( int i = 0; i < tmpCity->getDegree(); i++)
{
//if the current city's distance + 1 is less than the curr. distance of its neighbor, do relaxation
if (this->distances[ tmpCity->getId() ] + 1 < this->distances[ tmpCity->getNeighborIds()[i] ] )
{
this->prevs[ tmpCity->getNeighborIds()[i] ] = tmpCity->getId();
this->distances[ tmpCity->getNeighborIds()[i] ] = this->distances[ tmpCity->getId() ] + 1;
}
this->printCurrDistAndPrevs();
}
// if there is even a single path which is not completed so far, continue to process
isDone = true;
cout << "\n------\ncompletedPaths: ";
for(int i = 0; i < this->numVertices; i++)
{
cout << (completedPaths[i] ? "1 " : "0 ");
if( !completedPaths[i] )
{
isDone = false;
break;
}
}
cout << "\n" << endl;
}
delete []completedPaths;
}