Notes

@Override
public Collection<V> getSuccessors(V vertex) {
// Check if vertex exists
if (!adjacencyMap.containsKey(vertex)) {
return null;
}

MinHeap<Destination<V>> edgeHeap = adjacencyMap.get(vertex);
LinkedList<V> successors = new LinkedList<>();

// Create a temporary heap to avoid modifying the original
MinHeap<Destination<V>> tempHeap = new MinHeap<>(edgeHeap);

// Extract all destinations while preserving priority order
while (!tempHeap.isEmpty()) {
Destination<V> dest = tempHeap.poll();
successors.add(dest.node);
}

return successors;
}

// Add helper method to detect cycles
private boolean hasCycle(V vertex, HashSet<V> visited, HashSet<V> recursionStack) {
if (!visited.contains(vertex)) {
visited.add(vertex);
recursionStack.add(vertex);

Collection<V> successors = getSuccessors(vertex);
if (successors != null) {
for (V successor : successors) {
if (!visited.contains(successor) && hasCycle(successor, visited, recursionStack)) {
return true;
} else if (recursionStack.contains(successor)) {
return true;
}
}
}
}
recursionStack.remove(vertex);
return false;
}

// Public method to check for cycles
public boolean hasCycle() {
HashSet<V> visited = new HashSet<>();
HashSet<V> recursionStack = new HashSet<>();

for (V vertex : getVertices()) {
if (hasCycle(vertex, visited, recursionStack)) {
return true;
}
}
return false;
}