Method add_edge

code/graph/edmonds_karps_mcmf.cpp:12–16

  flow_network(int _n) : n(_n), head(n,-1) { }
  void reset() { e = e_store; }
  void add_edge(int u, int v, int cost, int uv, int vu=0) {
    e.push_back(edge(v, uv, cost, head[u]));
    head[u] = (int)size(e)-1;
    e.push_back(edge(u, vu, -cost, head[v]));
    head[v] = (int)size(e)-1; }
  ii min_cost_max_flow(int s, int t, bool res=true) {
    e_store = e;
    memset(pot, 0, n*sizeof(int));