Why its not working with negative weights ? #11
Description
`g.addEdge(new jsgraphs.Edge(0,1,1));
g.addEdge(new jsgraphs.Edge(1,0,-1));
g.addEdge(new jsgraphs.Edge(1,2,1));
g.addEdge(new jsgraphs.Edge(2,1,-1));
g.addEdge(new jsgraphs.Edge(2,3,1));
g.addEdge(new jsgraphs.Edge(3,2,-1));
g.addEdge(new jsgraphs.Edge(3,1,1));
g.addEdge(new jsgraphs.Edge(1,3,-1));`