struct bounded_mcmf { int n, m, S, T; mcmf net; ll sum; vector fl; vector init; vector costs; bounded_mcmf(int n, int m) : sum(0), n(n), m(m), S(0), T(n + 1), net(n + 1), fl(m), init(n + 1), costs(m) {} // handle negative loop case void add_edge(int from, int to, ll low, ll high, ll cost, int edge_id = -1) { if (cost < 0) { __add_edge(from, to, high, high, cost, -1); __add_edge(to, from, 0, high - low, -cost, edge_id); } else { __add_edge(from, to, low, high, cost, edge_id); } if (edge_id != -1) { costs[edge_id] = cost; if (cost < 0) { fl[edge_id] += high; // RealFlow = UpperBound - Flow } else { fl[edge_id] += low; // RealFlow = LowerBound + Flow } } } void __add_edge(int from, int to, ll low, ll high, ll cost, int edge_id = -1) { net.add_edge(from, to, high - low, cost, edge_id, -1); init[to] += low, init[from] -= low; } void prep(int s, int t) { for (int i = 1; i <= n; ++i) { if (init[i] > 0) { net.add_edge(S, i, init[i], 0, -1, -1); sum += init[i]; } else if (init[i] < 0) { net.add_edge(i, T, -init[i], 0, -1, -1); } } net.add_edge(t, s, INFLL, 0, -1, -1); } // min-cost max-flow optional>> run_mcmf(int s, int t) { // BUG: unchecked code prep(s, t); if (sum != net.run(S, T).first) { return nullopt; } else { auto [res_flow, res_cost] = net.run(s, t); for (int from = 1; from <= n; ++from) { for (auto&& [to, cap, flow, cost, rev, mark] : net.edges[from]) { if (mark != -1) { if (costs[mark] < 0) { fl[mark] -= flow; } else { fl[mark] += flow; } } } } return {{res_flow, res_cost, fl}}; } } // min-cost flow optional>> run_mcf(int s, int t) { prep(s, t); auto [res_flow, res_cost] = net.run(S, T); if (sum != res_flow) { return nullopt; } else { for (int from = 1; from <= n; ++from) { for (auto&& [to, cap, flow, cost, rev, mark] : net.edges[from]) { if (mark != -1) { if (costs[mark] < 0) { fl[mark] -= flow; } else { fl[mark] += flow; } } } } return {{res_flow, res_cost, fl}}; } } };