connected components of triangle faces in a mesh
I have implemented depth first search using the above link and works fine for most of my data samples. When my data sample is very large, the code reaches a break point, likely to be stack overflow as the recursive function gets too deep. Is there any way to avoid this? or do I have to use some other way like breadth first search / union find algorithm to find connected components in a graph.
#include <bits/stdc .h>
using namespace std;
class Graph {
// A function used by DFS
void DFSUtil(int v);
public:
int count;
map<int, bool> visited;
map<int, list<int> > adj;
// function to add an edge to graph
void addEdge(int v, int w);
// prints DFS traversal of the complete graph
void DFS();
};
void Graph::addEdge(int v, int w)
{
adj[v].push_back(w); // Add w to v’s list.
}
void Graph::DFSUtil(int v)
{
// Mark the current node as visited and print it
visited[v] = true;
cout << v << " ";
// Recur for all the vertices adjacent to this vertex
list<int>::iterator i;
for (i = adj[v].begin(); i != adj[v].end(); i)
if (!visited[*i])
DFSUtil(*i);
}
// The function to do DFS traversal. It uses recursive
// DFSUtil()
void Graph::DFS()
{
count = 0;
// Call the recursive helper function to print DFS
// traversal starting from all vertices one by one
for (auto i : adj)
if (visited[i.first] == false)
{
DFSUtil(i.first);
count ;
}
}
int main()
{
// Create a graph given in the above diagram
Graph g;
for face in faces :
{
g.addEdge(face[0], face[1]);
g.addEdge(face[0], face[2]);
g.addEdge(face[1], face[0]);
g.addEdge(face[1], face[2]);
g.addEdge(face[2], face[0]);
g.addEdge(face[2], face[1]);
}
cout << "Following is Depth First Traversal \n";
// Function call
g.DFS();
cout << "number of connected components = " << g.count << "\n";
return 0;
}
CodePudding user response:
With a recursive algorithm, there is no way to avoid a stack overflow. But, you need to re-implement your algo with an iterative version using a stack.
Here is a rough implementation .
void Graph::DFSUtil(int v)
{
stack<int> stack;
stack.push(v);
cout << v << " ";
while (!stack.empty())
{
int v = stack.top();
stack.pop();
if (!visited[v])
{
cout << v << " ";
visited[v] = true;
}
for (int i = adj[v].begin(); i != adj[v].end(); i)
if (!visited[*i])
stack.push(*i);
}
}