Depth first and breadth first algorithm

Source: Internet
Author: User

Graph traversal has depth-first and breadth-first algorithm.

Depth-first traversal can be described as a recursive algorithm. When the vertex v is reached, the specific operation is:

① access (v);

②for (w) for each vertex (W) adjacent to V;

  

Depth-First algorithm template<int max_size>void diagraph<max_size>::d epth_first (void (*visit) (Vertex &)) const { BOOL Visited[max_size]; The introduction of arrays prevents infinite loops vertex v;for (all v in g) visited[v] = False;for (all v in g) {if (!visited[v]) {traverse (V, visited, visit);} }}template<int max_size>void diagraph<max_size>::traverse (Vertex &v, bool Visited[],void (*visit) ( Vertex &)) const {Vertex W;visited[v] = true; (*visit) (v); for (all w adjacent to V) {if (!visited[w]) {traverse (W, Visi Ted, visit);}}}

The breadth-first algorithm uses a queue that, when accessed V, appends the remaining unreachable vertices of V to the queue, and then accesses the queue header:

Breadth-First algorithm template<int max_size>void diagraph<max_size>::breadth_first (void (*visit) (Vertex &)) const {Queue Q;bool visited[max_size]; Vertex V, W, x;for (all V in grams) visited[v] = False;for (all v in g) {if (!visited[v]) {q.append (v); while (!q.empty ()) {Q.R Etrieve (W), if (!visited[w]) {visited[w] = true; (*visit) (w); for (all x adjacent to W) {q.append (x);}} Q.serve ();}}}

You can use depth-first traversal and breadth-first traversal to determine the topological order.

Depth-First traversal: Time complexity O (n+e) (n is the fixed-point number of the graph, and E is the number of sides of the graph).

Depth-First algorithm template<int graph_size>void diagraph<graph_size>:: Depth_sort (list<vertex>& Topological_order) {bool Visited[graph_size]; Vertex v;for (v = 0; v < count; v++) Visited[v] = False;topological_order.clear (); for (v = 0; v < count; v++) {if (! Visited[v]) {Recursive_depth_sort (V, visited, Topological_order);}}} Template<int max_size>void Diagraph<max_size>::recursive_depth_sort (Vertex V, bool *visited, List<  vertex>& topological_order) {visited[v] = True;int degree = neighbors[v].size (); for (int i = 0; i < degree; i++) {Vertex W;neighbors[v].retrieve (i, W), if (!visited[w]) {recursive_depth_sort (W, visited, Topological_order);}} Topological_order.insert (0, v);}

Depth first and breadth first algorithm

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.