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Templatize Graph class #21

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Templatize Graph class #21

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31 changes: 16 additions & 15 deletions dijkstras.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,24 +6,25 @@

using namespace std;

template<typename VertexT = char, typename DistanceT = int>
class Graph
{
unordered_map<char, const unordered_map<char, int>> vertices;
unordered_map<VertexT, const unordered_map<VertexT, DistanceT>> vertices;

public:
void add_vertex(char name, const unordered_map<char, int>& edges)
void add_vertex(VertexT name, const unordered_map<VertexT, DistanceT>& edges)
{
vertices.insert(unordered_map<char, const unordered_map<char, int>>::value_type(name, edges));
vertices.insert(typename unordered_map<VertexT, const unordered_map<VertexT, DistanceT>>::value_type(name, edges));
}

vector<char> shortest_path(char start, char finish)
vector<VertexT> shortest_path(VertexT start, VertexT finish)
{
unordered_map<char, int> distances;
unordered_map<char, char> previous;
vector<char> nodes;
vector<char> path;
unordered_map<VertexT, DistanceT> distances;
unordered_map<VertexT, VertexT> previous;
vector<VertexT> nodes;
vector<VertexT> path;

auto comparator = [&] (char left, char right) { return distances[left] > distances[right]; };
auto comparator = [&] (VertexT left, VertexT right) { return distances[left] > distances[right]; };

for (auto& vertex : vertices)
{
Expand All @@ -33,7 +34,7 @@ class Graph
}
else
{
distances[vertex.first] = numeric_limits<int>::max();
distances[vertex.first] = numeric_limits<DistanceT>::max();
}

nodes.push_back(vertex.first);
Expand All @@ -43,7 +44,7 @@ class Graph
while (!nodes.empty())
{
pop_heap(begin(nodes), end(nodes), comparator);
char smallest = nodes.back();
VertexT smallest = nodes.back();
nodes.pop_back();

if (smallest == finish)
Expand All @@ -57,14 +58,14 @@ class Graph
break;
}

if (distances[smallest] == numeric_limits<int>::max())
if (distances[smallest] == numeric_limits<DistanceT>::max())
{
break;
}

for (auto& neighbor : vertices[smallest])
{
int alt = distances[smallest] + neighbor.second;
DistanceT alt = distances[smallest] + neighbor.second;
if (alt < distances[neighbor.first])
{
distances[neighbor.first] = alt;
Expand All @@ -80,7 +81,7 @@ class Graph

int main()
{
Graph g;
Graph<> g;
g.add_vertex('A', {{'B', 7}, {'C', 8}});
g.add_vertex('B', {{'A', 7}, {'F', 2}});
g.add_vertex('C', {{'A', 8}, {'F', 6}, {'G', 4}});
Expand All @@ -90,7 +91,7 @@ int main()
g.add_vertex('G', {{'C', 4}, {'F', 9}});
g.add_vertex('H', {{'E', 1}, {'F', 3}});

for (char vertex : g.shortest_path('A', 'H'))
for (const auto& vertex : g.shortest_path('A', 'H'))
{
cout << vertex << endl;
}
Expand Down