From ed19bc6a85bba631a04e3fb3f7a1c4a505e2c548 Mon Sep 17 00:00:00 2001
From: subcrip <contact@subc.rip>
Date: Sun, 19 May 2024 14:37:06 +0800
Subject: [PATCH] Add graph/examples/active_flow_with_demands.cc

Signed-off-by: subcrip <contact@subc.rip>
---
 graph/examples/active_flow_with_demands.cc | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 graph/examples/active_flow_with_demands.cc

diff --git a/graph/examples/active_flow_with_demands.cc b/graph/examples/active_flow_with_demands.cc
new file mode 100644
index 0000000..6bdbeb7
--- /dev/null
+++ b/graph/examples/active_flow_with_demands.cc
@@ -0,0 +1,31 @@
+struct dinic {
+    // ...
+};
+
+void solve() {
+    read(int, n, m, s, t);
+    dinic net(n + 1);
+    int S = 0, T = n + 1;
+    vector<int> init(n + 1);
+    for (int i = 0 ;i  < m; ++i) {
+        read(int, u, v, lower, upper);
+        init[v] += lower;
+        init[u] -= lower;
+        net.add_edge(u, v, upper - lower);
+    }
+    int sum = 0;
+    for (int i  =1; i <= n; ++i) {
+        if (init[i] > 0) {
+            net.add_edge(S, i, init[i]);
+            sum += init[i];
+        } else if (init[i] < 0) {
+            net.add_edge(i, T, -init[i]);
+        }
+    }
+    net.add_edge(t, s, INF);  // WARN: s->t is wrong
+    if (sum != net.run(S, T)) {
+        cout << "please go home to sleep\n";
+    } else {
+        cout << net.run(s, t) << '\n';
+    }
+}