From 8b0726e6304dfe9f4c63567cb6f8f778bc12b9c9 Mon Sep 17 00:00:00 2001
From: tht2005 <75089048+tht2005@users.noreply.github.com>
Date: Sun, 25 Aug 2024 12:28:49 +0700
Subject: [PATCH 1/5] Update MinCostMaxFlow.h

Fix a bug that occur when maxflow function is called multiple times from different source vertices.
---
 content/graph/MinCostMaxFlow.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/content/graph/MinCostMaxFlow.h b/content/graph/MinCostMaxFlow.h
index 23819ceed..29f081979 100644
--- a/content/graph/MinCostMaxFlow.h
+++ b/content/graph/MinCostMaxFlow.h
@@ -34,6 +34,7 @@ struct MCMF {
 	}
 
 	void path(int s) {
+		fill(all(par), 0);
 		fill(all(seen), 0);
 		fill(all(dist), INF);
 		dist[s] = 0; ll di;

From 18ac9ac14e016c3b70519c69503a620ff8d3c4ad Mon Sep 17 00:00:00 2001
From: tht2005 <75089048+tht2005@users.noreply.github.com>
Date: Sun, 25 Aug 2024 12:48:36 +0700
Subject: [PATCH 2/5] Update MinCostMaxFlow.h

---
 content/graph/MinCostMaxFlow.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/content/graph/MinCostMaxFlow.h b/content/graph/MinCostMaxFlow.h
index 29f081979..b2bceb647 100644
--- a/content/graph/MinCostMaxFlow.h
+++ b/content/graph/MinCostMaxFlow.h
@@ -34,9 +34,9 @@ struct MCMF {
 	}
 
 	void path(int s) {
-		fill(all(par), 0);
 		fill(all(seen), 0);
 		fill(all(dist), INF);
+		rep(i, 0, sz(par)) par[i] = NULL;
 		dist[s] = 0; ll di;
 
 		__gnu_pbds::priority_queue<pair<ll, int>> q;

From 1517c54be718272d908f55a327988421ea9baa33 Mon Sep 17 00:00:00 2001
From: Nguyen Dinh Dang Duong <dangduong31205@gmail.com>
Date: Mon, 16 Sep 2024 03:43:02 +0700
Subject: [PATCH 3/5] fix par[s] = null

---
 content/graph/MinCostMaxFlow.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/content/graph/MinCostMaxFlow.h b/content/graph/MinCostMaxFlow.h
index b2bceb647..a867544ce 100644
--- a/content/graph/MinCostMaxFlow.h
+++ b/content/graph/MinCostMaxFlow.h
@@ -36,7 +36,7 @@ struct MCMF {
 	void path(int s) {
 		fill(all(seen), 0);
 		fill(all(dist), INF);
-		rep(i, 0, sz(par)) par[i] = NULL;
+		par[s] = NULL;
 		dist[s] = 0; ll di;
 
 		__gnu_pbds::priority_queue<pair<ll, int>> q;

From 95d915e7007533133afa8fc0b86904a663f4bd18 Mon Sep 17 00:00:00 2001
From: Nguyen Dinh Dang Duong <dangduong31205@gmail.com>
Date: Mon, 16 Sep 2024 04:03:02 +0700
Subject: [PATCH 4/5] add multiple maxflow call with different (S, T) tests for
 mcmf

---
 stress-tests/graph/MinCostMaxFlow.cpp | 35 +++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/stress-tests/graph/MinCostMaxFlow.cpp b/stress-tests/graph/MinCostMaxFlow.cpp
index 17c96426b..d68f83c10 100644
--- a/stress-tests/graph/MinCostMaxFlow.cpp
+++ b/stress-tests/graph/MinCostMaxFlow.cpp
@@ -201,7 +201,42 @@ void testNeg() {
 	cout<<"Tests passed!"<<endl;
 }
 
+void testMultiSource() {
+	const int ITS = 100;
+	const int TRY = 15;
+
+	rep(it, 0, ITS) {
+		size_t lasti = ::i;
+		int N = rand() % 7 + 2;
+		int M = rand() % 17;
+		int S = 0, T = 1;
+		MCMF mcmf(N);
+		rep(im, 0, M) {
+			int i, j;
+			do {
+				i = rand() % N;
+				j = rand() % N;
+			} while(i == j);
+			int fl = rand() % 50;
+			int co = rand() % 30;
+			mcmf.addEdge(i, j, fl, co);
+		}
+		rep(test, 0, TRY) {
+			int S, T;
+			do {
+				S = rand() % N;
+				T = rand() % N;
+			} while(S == T);
+			mcmf.maxflow(S, T);
+		}
+		::i = lasti;
+	}
+	cout<<"Tests passed!"<<endl;
+}
+
 int main() {
 	testMatching();
 	testNeg();
+	testMultiSource();
+	return 0;
 }

From 909cb36526c89145b3727a9a3d5510dd20fd4db3 Mon Sep 17 00:00:00 2001
From: Nguyen Dinh Dang Duong <dangduong31205@gmail.com>
Date: Mon, 23 Sep 2024 03:07:52 +0700
Subject: [PATCH 5/5] change par[s] = NULL to par[s] = 0

---
 content/graph/MinCostMaxFlow.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/content/graph/MinCostMaxFlow.h b/content/graph/MinCostMaxFlow.h
index a867544ce..7912797df 100644
--- a/content/graph/MinCostMaxFlow.h
+++ b/content/graph/MinCostMaxFlow.h
@@ -36,7 +36,7 @@ struct MCMF {
 	void path(int s) {
 		fill(all(seen), 0);
 		fill(all(dist), INF);
-		par[s] = NULL;
+		par[s] = 0;
 		dist[s] = 0; ll di;
 
 		__gnu_pbds::priority_queue<pair<ll, int>> q;