Method flow_network

code/graph/edmonds_karps.cpp:8–9

      : v(_v), nxt(_nxt), cap(_cap) { } };
  int n, *head; vector<edge> e, e_store;
  flow_network(int _n) : n(_n) {
    memset(head = new int[n], -1, n*sizeof(int)); }
  void reset() { e = e_store; }
  void add_edge(int u, int v, int uv, int vu=0) {
    e.push_back(edge(v,uv,head[u])); head[u]=(int)size(e)-1;