Dinic's algorithm implementation

dinic.cpp

@@ -0,0 +1,62 @@
+const int N = 500;
+const int M = 10000;
+
+int n, m;
+struct Edge {
+  int v, u, c, f = 0;
+  Edge() {}
+  Edge(int v, int u, int c) : v(v), u(u), c(c) {}
+  int cf() { return c - f; }
+} e[2 * M];
+vector<int> g[N];
+int s, t;
+
+int df;
+
+int dist[N];
+
+bool bfs() {
+  queue<int> q;
+  q.push(s);
+  fill(dist, dist + n, -1);
+  dist[s] = 0;
+  while (!q.empty()) {
+    int v = q.front();
+    q.pop();
+    for (int i : g[v]) {
+      if (e[i].cf() >= df && dist[e[i].u] == -1) {
+        dist[e[i].u] = dist[v] + 1;
+        q.push(e[i].u);
+      }
+    }
+  }
+  return dist[t] != -1;
+}
+
+int ptr[N];
+
+bool dfs(int v) {
+  if (v == t) {
+    return true;
+  }
+  for (; ptr[v] < g[v].size(); ++ptr[v]) {
+    int i = g[v][ptr[v]];
+    if (dist[v] + 1 == dist[e[i].u] && e[i].cf() >= df && dfs(e[i].u)) {
+      e[i].f += df;
+      e[i ^ 1].f -= df;
+      return true;
+    }
+  }
+  return false;
+}
+
+void dinic() {
+  const int K = 30;
+  for (df = 1 << K; df >= 1; df >>= 1) {
+    while (bfs()) {
+      fill(ptr, ptr + N, 0);
+      while (dfs(s)) {
+      }
+    }
+  }
+}