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source/Graph/Dinic.cpp

@@ -0,0 +1,69 @@
+struct Edge {
+    int to, cap, now;
+    Edge* rev;
+    Edge(int to,int cap):to(to), cap(cap), now(0){}
+    int left(){return cap - now;}
+    void flow(int f){now += f; rev->now -= f;}
+    void reset(){now = 0;}
+};
+vector<Edge*> adj[N];
+
+int lv[N]; bool chk[N];
+bool bfs(int S, int T) {
+    queue<int> q;
+    q.push(S); lv[S] = 0; chk[S] = true;
+    while(!q.empty()) {
+        int s = q.front(); q.pop();
+        for(auto i : adj[s]) {
+            if(i->left() and !chk[i->to]) {
+                lv[i->to] = lv[s]+1; chk[i->to] = true;
+                q.push(i->to);
+            }
+        }
+    }
+    return chk[T];
+}
+
+Edge* hist[N]; int last[N];
+bool dfs(int s, int T) {
+    if(s == T) return true;
+
+    for(int &j=last[s]; j < adj[s].size(); j++) {
+        int i = adj[s][j]->to;
+        if(adj[s][j]->left() == 0 or lv[i] != lv[s]+1) continue;
+        hist[i] = adj[s][j];
+
+        if(dfs(i, T)) return true;
+    }
+    return false;
+}
+
+ll flow(int S,int T) {
+    ll ans = 0;
+    while(bfs(S, T)) {
+        while(dfs(S, T)) {
+            int m = 2e9;
+            int now = T;
+            while(S != now) {
+                m = min(m, hist[now]->left());
+                now = hist[now]->rev->to;
+            }
+            now = T;
+            while(S != now)
+                hist[now]->flow(m), now = hist[now]->rev->to;
+            ans += m;
+        } 
+        memset(last, 0, sizeof last);
+        memset(chk, 0, sizeof chk);
+    }
+    return ans;
+}
+// isDir : isDirected => 양방향 간선이면 false
+void connect(int from, int to, int cap, bool isDir = true) {
+    Edge *fw, *bw;
+    fw = new Edge(to, cap);
+    bw = new Edge(from, !isDir ? cap : 0);
+    fw->rev = bw; bw->rev = fw;
+    adj[from].push_back(fw);
+    adj[to].push_back(bw);
+}