void scn::RunSPFA(UGraph::pGraph graph,size_t indexOfSource, std::unordered_map<size_t,size_t> &distance)
{
assert(graph->HasNode(indexOfSource));
// Map<size_t>& distance = distance_sssp;
//distance, stored the distance information of each node
//init
for(auto node = graph->begin(); node != graph->end(); node++)
{
distance[*node] = Graph::NaF;
}
distance[indexOfSource] = 0;
queue<size_t> queue_buffer;
unordered_set<size_t> in_queue;
queue_buffer.push(indexOfSource);//push source node
size_t front;
while(!queue_buffer.empty())
{
front = queue_buffer.front();
queue_buffer.pop();
in_queue.erase(front);
auto node = graph->find(front);
for(auto other = node->begin(); other != node->end(); other++)
{
if(in_queue.find(*other) == in_queue.end() &&
distance[front] + 1 < distance[*other])
{
distance[*other] = distance[front] + 1;
queue_buffer.push(*other);
in_queue.insert(*other);
}
}
}
}
double scn::GetSearchInfo(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget)
{
assert(graph->HasNode(indexOfSource));
assert(graph->HasNode(indexOfTarget));
assert(indexOfSource != indexOfTarget);
std::unordered_map<size_t,size_t> distance;
//get shortest distance
//auto& distance = distance_sssp;
RunSPFA(graph,indexOfSource,distance);
double sum = 0;
//search in breadth-first way
queue<pair<size_t, double>> path_queue;//pair : indexOfNode,
//probability of path
path_queue.push(make_pair(indexOfTarget, 1.0));
while(!path_queue.empty())
{
auto current = path_queue.front();
auto node = (*graph)[current.first];
path_queue.pop();
for(auto other = node->begin(); other != node->end(); other++)
{//put all of previous-node in path into queue
if(distance[*other] == distance[*node] - 1)
{
if(distance[*other] == 0)
sum += current.second / static_cast<double>(node->GetDegree());
else
path_queue.push(make_pair(*other, current.second /
static_cast<double>((*graph)[*other]->GetDegree() - 1)));
}
}
}
return - log(sum)/log(2.0);
}
size_t scn::GetShortestDistance(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget)
{
assert(graph->HasNode(indexOfSource) && graph->HasNode(indexOfTarget));
//breadth-first search
queue<size_t> search_queue;
std::unordered_map<size_t,size_t> distance;
unordered_set<size_t> in_queue;
size_t front;
//initial
distance[indexOfSource] = 0;
search_queue.push(indexOfSource);
in_queue.insert(indexOfSource);
while(!search_queue.empty())
{
front = search_queue.front();
search_queue.pop();
in_queue.erase(front);
auto node = graph->find(front);
for(auto other = node->begin(); other != node->end(); other++)
{
if(*other == indexOfTarget)
return distance[*node] + 1;
if(in_queue.find(*other) == in_queue.end() &&
(distance.find(*other) == distance.end() || distance[front] + 1 < distance[*other]))
{
distance[*other] = distance[front] + 1;
search_queue.push(*other);
in_queue.insert(*other);
}
}
}
//if this point is reached, the indexOfTarget is an isolated node
return Graph::NaF;
}
void scn::RunDjikstra(UGraph::pGraph graph,size_t indexOfSource,std::unordered_map<size_t,size_t> &distance)
{
//auto& distance = distance_sssp;//using distance_sssp eariler
assert(graph->HasNode(indexOfSource));
//init
//distance.reserve(graph->GetNumberOfNodes());
for(auto node = graph->begin(); node != graph->end(); node++)
{
distance[*node] = Graph::NaF;
}
distance[indexOfSource] = 0;
list<size_t> queue;
//fill index of nodes into queue
for(size_t i = 0; i < graph->GetNumberOfNodes(); i++)
{
queue.push_back(i);
}
//begin
size_t next_distance;
while(!queue.empty())
{
//get min one
auto min = min_element(queue.begin(), queue.end(),
[&](const size_t &one, const size_t &two)->bool
{
if(distance[one] < distance[two])
return true;
else
return false;
});
auto node = graph->find(*min);
if(distance[*node] < Graph::NaF)
next_distance = distance[*node] + 1;
else
next_distance = Graph::NaF;
//relax neighbors
for(auto other = node->begin(); other != node->end(); other++)
{
if(distance[*other] > next_distance)
{
distance[*other] = next_distance;
}
}
queue.erase(min);
}
}
pair<size_t, size_t> scn::GetNumberOfShortestPath(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget,
size_t indexOfThrough)
{
assert(graph->HasNode(indexOfSource));
assert(graph->HasNode(indexOfTarget));
//find shortest path
std::unordered_map<size_t,size_t> distance;
//auto& distance = distance_sssp;
RunSPFA(graph,indexOfSource,distance);
if(indexOfThrough == UGraph::NaF)
{//no passing through any specified node
size_t sum = 0;
queue<size_t> path;
path.push(indexOfTarget);
//breadth-first search
while(!path.empty())
{
if(indexOfSource == path.front())
sum++;
else
{
auto current = graph->find(path.front());
size_t current_distance = distance[*current];
for(auto other = current->begin(); other != current->end(); other++)
{
if(distance[*other] == current_distance - 1)
path.push(*other);
}
}
path.pop();
}
return make_pair(sum, sum);
}
else
{
assert(graph->HasNode(indexOfThrough));
assert(indexOfSource != indexOfThrough);
assert(indexOfTarget != indexOfThrough);
size_t sum_all = 0;
size_t sum_through = 0;
queue<pair<size_t, bool>> path;//pair(indexOfNode, Does it Pass
//through the give node?
path.push(make_pair(indexOfTarget, false));
//breadth-first search
while(!path.empty())
{
auto current = path.front();
if(current.first == indexOfThrough)
current.second = true;
if(indexOfSource == current.first)
{
sum_all++;
if(current.second)
sum_through++;
}
else
{
size_t current_distance = distance[current.first];
auto current_node = graph->find(current.first);
for(auto other = current_node->begin(); other != current_node->end(); other++)
{
if(distance[*other] == current_distance - 1)
path.push(make_pair(*other, current.second));
}
}
path.pop();
}
return make_pair(sum_all, sum_through);
}
}
