Algorithm-Implementations/UndirectedGraphs.java at master · devForTheFuture/Algorithm-Implementations · GitHub

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packagealgorithms;

importjava.util.*;


/**
 * Implementation of undirected graph represented using adjacency list.
 *
 * @author joeytawadrous
 */
publicfinalclassUndirectedGraphs<T> implementsIterable<T>
{
privatefinalMap<T, Set<T>> graph = newHashMap<T, Set<T>>();

publicbooleanaddNode(Tnode)
 {
if (graph.containsKey(node)) { returnfalse; }

graph.put(node, newHashSet<T>());

returntrue;
 }

publicvoidaddEdge(Tstart, Tdest)
 {
if (!graph.containsKey(start) || !graph.containsKey(dest))
 {
System.out.println("No such nodes in the graph.");
 }
else
 {
graph.get(start).add(dest);
graph.get(dest).add(start);
 }
 }

publicvoidremoveEdge(Tstart, Tdest)
 {
if (!graph.containsKey(start) || !graph.containsKey(dest))
 {
System.out.println("No such nodes in the graph.");
 }
else
 {
graph.get(start).remove(dest);
graph.get(dest).remove(start);
 }
 }

publicbooleanisEdgeExists(Tstart, Tend)
 {
if (!graph.containsKey(start) || !graph.containsKey(end))
 {
System.out.println("No such nodes in the graph.");
 }

returngraph.get(start).contains(end);
 }

publicSet<T> getNeighbors(Tnode)
 {
Set<T> neighbors = graph.get(node);

if (neighbors == null)
 {
System.out.println("No such nodes in the graph.");
 }

returnCollections.unmodifiableSet(neighbors);
 }

publicIterator<T> iterator()
 {
returngraph.keySet().iterator();
 }

publicIterable<T> getNodes()
 {
returngraph.keySet();
 }

publicintsize()
 {
returngraph.size();
 }

publicbooleanisEmpty()
 {
returngraph.isEmpty();
 }
}