// Input: a directed graph G s.t.
// for all edge e, e.cost is a real number and no negative
// cycles and a starting node n
//
// At the beginning we assume all backpointers to be NIL
// and for each node n, n.cost to be +infinity
//
// Output: a modified graph G s.t. for all nodes m reachable
// from n in G, n.backpointer points to the previous node
// in a path of minimal cost from n to m
//
// FordFulkerson \in O(|E|*|V|)
FordFulkerson(G,n) {
   n.cost := 0
   for each v in V do
      for each (u,w) in E of cost k do
         if u.cost + k < w.cost then
            w.cost := u.cost + k
            w.backpointer := u
}