40 lines
1.2 KiB
C++
40 lines
1.2 KiB
C++
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struct bounded_flow {
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int n, m, S, T;
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dinic net;
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ll sum;
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vector<ll> fl;
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vector<ll> init;
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bounded_flow(int n, int m) : sum(0), n(n), m(m), S(0), T(n + 1), net(n + 1), fl(m), init(n + 1) {}
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void add_edge(int from, int to, ll low, ll high, int edge_id = -1) {
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if (edge_id != -1) {
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fl[edge_id] += low;
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}
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net.add_edge(from, to, high - low, edge_id, -1);
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init[to] += low, init[from] -= low;
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}
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optional<pair<ll, vector<ll>>> run(int s, int t) {
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for (int i = 1; i <= n; ++i) {
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if (init[i] > 0) {
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net.add_edge(S, i, init[i], -1, -1);
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sum += init[i];
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} else if (init[i] < 0) {
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net.add_edge(i, T, -init[i], -1, -1);
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}
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}
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net.add_edge(t, s, INFLL, -1, -1);
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if (sum != net.run(S, T)) {
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return nullopt;
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} else {
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auto res_flow = net.run(s, t);
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for (int from = 1; from <= n; ++from) {
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for (auto&& [to, cap, flow, rev, mark] : net.edges[from]) {
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if (mark != -1) {
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fl[mark] = flow;
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}
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}
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}
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return {{res_flow, fl}};
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}
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}
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};
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