/**
* Determines a depth-first order for the edge-weighted digraph <tt>G</tt>.
*
* @param G the edge-weighted digraph
*/
public DepthFirstOrder(MapGraph G) {
pre = new int[G.V()];
post = new int[G.V()];
postorder = new Queue<Integer>();
preorder = new Queue<Integer>();
marked = new boolean[G.V()];
for (int v = 0; v < G.V(); v++) if (!marked[v]) dfs(G, v);
}
private void dfs(MapGraph G, int v) {
marked[v] = true;
pre[v] = preCounter++;
preorder.enqueue(v);
for (MapEdge e : G.adj(v)) {
int w = e.to();
if (!marked[w]) {
dfs(G, w);
}
}
postorder.enqueue(v);
post[v] = postCounter++;
}