72 lines
1.8 KiB
C++
72 lines
1.8 KiB
C++
struct dinic {
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struct edge {
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int to;
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ll cap;
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ll flow;
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int rev;
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int mark;
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};
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vector<vector<edge>> edges;
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vector<int> layer;
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vector<bool> vis;
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dinic(int n) : edges(n + 1), layer(n + 1), vis(n + 1) {}
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void add_edge(int from, int to, ll cap, int mark = 0) {
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edges[from].push_back({ to, cap, 0, int(edges[to].size()), mark });
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edges[to].push_back({ from, 0, 0, int(edges[from].size() - 1), mark });
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}
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bool bfs(int s, int t) {
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layer.assign(edges.size(), 0);
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deque<pii> dq;
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layer[s] = 1;
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dq.emplace_back(s, 1);
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while (dq.size()) {
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popfront(dq, v, l);
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for (auto&& e : edges[v]) {
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if (layer[e.to] == 0 and e.cap > e.flow) {
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layer[e.to] = l + 1;
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dq.emplace_back(e.to, l + 1);
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}
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}
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}
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return layer[t] != 0;
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}
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ll dfs(int s, int t, ll cap) {
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if (vis[s]) {
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return 0;
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}
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vis[s] = 1;
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if (s == t) {
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return cap;
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}
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ll res = 0;
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int n = edges[s].size();
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for (int i = 0; i < n; ++i) {
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auto e = edges[s][i];
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if (e.cap > e.flow and layer[e.to] == layer[s] + 1) {
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ll nw = dfs(e.to, t, min(cap - res, e.cap - e.flow));
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edges[s][i].flow += nw;
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edges[e.to][e.rev].flow -= nw;
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res += nw;
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if (res == cap) {
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return res;
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}
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}
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}
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return res;
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}
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ll run(int s, int t) {
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ll res = 0;
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while (bfs(s, t)) {
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vis.assign(edges.size(), 0);
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res += dfs(s, t, LLONG_MAX);
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}
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return res;
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}
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};
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