/**
* Contracts the edges incidents on the vertices {@code s} and {@code t} of
* the given edge-weighted graph.
*
* @param G the edge-weighted graph
* @param s the vertex {@code s}
* @param t the vertex {@code t}
* @return a new edge-weighted graph for which the edges incidents on the
* vertices {@code s} and {@code t} were contracted
*/
private EdgeWeightedGraph contractEdge(EdgeWeightedGraph G, int s, int t) {
EdgeWeightedGraph H = new EdgeWeightedGraph(G.V());
for (int v = 0; v < G.V(); v++) {
for (Edge e : G.adj(v)) {
int w = e.other(v);
if (v == s && w == t || v == t && w == s) continue;
if (v < w) {
if (w == t) H.addEdge(new Edge(v, s, e.weight()));
else if (v == t) H.addEdge(new Edge(w, s, e.weight()));
else H.addEdge(new Edge(v, w, e.weight()));
}
}
}
return H;
}