diff --git a/ortools/graph/BUILD.bazel b/ortools/graph/BUILD.bazel
index 1de87e6152..15cc51bd01 100644
--- a/ortools/graph/BUILD.bazel
+++ b/ortools/graph/BUILD.bazel
@@ -623,6 +623,7 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         "//ortools/base",
+        "//ortools/base:base_export",
         "//ortools/graph:iterators",
         "//ortools/util:permutation",
         "//ortools/util:zvector",
diff --git a/ortools/graph/connected_components.h b/ortools/graph/connected_components.h
index 1bb8a9418e..bba1ecd917 100644
--- a/ortools/graph/connected_components.h
+++ b/ortools/graph/connected_components.h
@@ -108,6 +108,10 @@ class DenseConnectedComponentsFinder {
   // Non-const because it does path compression internally.
   int FindRoot(int node);
 
+  // Returns the parent of the given node, in the chain towards the root of the
+  // set for this node. Returns the node itself if it is a root.
+  int GetParent(int node) const { return parent_[node]; }
+
   // Returns the same as GetConnectedComponents().
   std::vector<int> GetComponentIds();
 
diff --git a/ortools/graph/samples/BUILD.bazel b/ortools/graph/samples/BUILD.bazel
index 82ce60acd9..37d8c63ff0 100644
--- a/ortools/graph/samples/BUILD.bazel
+++ b/ortools/graph/samples/BUILD.bazel
@@ -18,6 +18,8 @@ load("@rules_java//java:java_binary.bzl", "java_binary")
 load("@rules_python//python:py_test.bzl", "py_test")
 load("//bazel:run_binary_test.bzl", "run_binary_test")
 
+package(default_visibility = ["//visibility:public"])
+
 cc_test(
     name = "assignment_linear_sum_assignment_test",
     srcs = ["assignment_linear_sum_assignment.cc"],
@@ -62,6 +64,7 @@ cc_test(
         "//ortools/base",
         "//ortools/graph:min_cost_flow",
         "@abseil-cpp//absl/base:log_severity",
+        "@abseil-cpp//absl/log",
         "@abseil-cpp//absl/log:globals",
     ],
 )
@@ -95,6 +98,7 @@ cc_test(
         "//ortools/base",
         "//ortools/graph:min_cost_flow",
         "@abseil-cpp//absl/base:log_severity",
+        "@abseil-cpp//absl/log",
         "@abseil-cpp//absl/log:globals",
     ],
 )
@@ -128,6 +132,7 @@ cc_test(
         "//ortools/base",
         "//ortools/graph:max_flow",
         "@abseil-cpp//absl/base:log_severity",
+        "@abseil-cpp//absl/log",
         "@abseil-cpp//absl/log:globals",
     ],
 )
@@ -164,6 +169,7 @@ cc_test(
         "//ortools/base",
         "//ortools/graph:min_cost_flow",
         "@abseil-cpp//absl/base:log_severity",
+        "@abseil-cpp//absl/log",
         "@abseil-cpp//absl/log:globals",
     ],
 )
@@ -203,6 +209,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dijkstra_directed_test",
+    binary = ":dijkstra_directed",
+    grep_lines = ["Shortest path length: 8"],
+)
+
 cc_binary(
     name = "dijkstra_undirected",
     srcs = ["dijkstra_undirected.cc"],
@@ -213,6 +225,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dijkstra_undirected_test",
+    binary = ":dijkstra_undirected",
+    grep_lines = ["Shortest path length: 4"],
+)
+
 cc_binary(
     name = "dijkstra_one_to_all",
     srcs = ["dijkstra_one_to_all.cc"],
@@ -224,6 +242,16 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dijkstra_one_to_all_test",
+    binary = ":dijkstra_one_to_all",
+    grep_lines = [
+        "Distance to 1: 2",
+        "Distance to 2: 6",
+        "Distance to 3: 2",
+    ],
+)
+
 cc_binary(
     name = "dijkstra_sequential",
     srcs = ["dijkstra_sequential.cc"],
@@ -236,6 +264,17 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dijkstra_sequential_test",
+    binary = ":dijkstra_sequential",
+    grep_lines = [
+        "Initial distance: 200",
+        "Distance_2_4: 2",
+        "Distance_8_1: 3",
+        "Distance_3_7: 4",
+    ],
+)
+
 cc_binary(
     name = "dijkstra_all_pairs_shortest_paths",
     srcs = ["dijkstra_all_pairs_shortest_paths.cc"],
@@ -251,6 +290,11 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dijkstra_all_pairs_shortest_paths_test",
+    binary = ":dijkstra_all_pairs_shortest_paths",
+)
+
 cc_binary(
     name = "dag_simple_shortest_path",
     srcs = ["dag_simple_shortest_path.cc"],
@@ -261,6 +305,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_simple_shortest_path_test",
+    binary = ":dag_simple_shortest_path",
+    grep_lines = ["Shortest path length: 2"],
+)
+
 cc_binary(
     name = "dag_shortest_path_one_to_all",
     srcs = ["dag_shortest_path_one_to_all.cc"],
@@ -276,6 +326,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_shortest_path_one_to_all_test",
+    binary = ":dag_shortest_path_one_to_all",
+    grep_lines = ["Length of shortest path to node 4: 2"],
+)
+
 cc_binary(
     name = "dag_shortest_path_sequential",
     srcs = ["dag_shortest_path_sequential.cc"],
@@ -287,6 +343,17 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_shortest_path_sequential_test",
+    binary = ":dag_shortest_path_sequential",
+    grep_lines = [
+        "Initial distance: 200",
+        "Distance_2_4: 2",
+        "Distance_8_1: 100",
+        "Distance_3_7: 4",
+    ],
+)
+
 cc_binary(
     name = "bfs_directed",
     srcs = ["bfs_directed.cc"],
@@ -300,6 +367,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "bfs_directed_test",
+    binary = ":bfs_directed",
+    grep_lines = ["Shortest path length (in arcs): 2"],
+)
+
 cc_binary(
     name = "bfs_undirected",
     srcs = ["bfs_undirected.cc"],
@@ -313,6 +386,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "bfs_undirected_test",
+    binary = ":bfs_undirected",
+    grep_lines = ["Shortest path length (in arcs): 2"],
+)
+
 cc_binary(
     name = "bfs_one_to_all",
     srcs = ["bfs_one_to_all.cc"],
@@ -326,6 +405,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "bfs_one_to_all_test",
+    binary = ":bfs_one_to_all",
+    grep_lines = ["Shortest path from 0 to 2 has length: 2"],
+)
+
 cc_binary(
     name = "root_a_tree",
     srcs = ["root_a_tree.cc"],
@@ -340,6 +425,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "root_a_tree_test",
+    binary = ":root_a_tree",
+    grep_lines = ["Depths:\n  0 -> 2"],
+)
+
 cc_binary(
     name = "rooted_tree_paths",
     srcs = ["rooted_tree_paths.cc"],
@@ -353,6 +444,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "rooted_tree_paths_test",
+    binary = ":rooted_tree_paths",
+    grep_lines = ["0 -> 4 [0, 1, 4]"],
+)
+
 cc_binary(
     name = "dag_simple_multiple_shortest_paths",
     srcs = ["dag_simple_multiple_shortest_paths.cc"],
@@ -363,6 +460,15 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_simple_multiple_shortest_paths_test",
+    binary = ":dag_simple_multiple_shortest_paths",
+    grep_lines = [
+        "#1 shortest path has length: 2",
+        "#2 shortest path has length: 3",
+    ],
+)
+
 cc_binary(
     name = "dag_multiple_shortest_paths_one_to_all",
     srcs = ["dag_multiple_shortest_paths_one_to_all.cc"],
@@ -378,6 +484,15 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_multiple_shortest_paths_one_to_all_test",
+    binary = ":dag_multiple_shortest_paths_one_to_all",
+    grep_lines = [
+        "\t#1 shortest path to node 4 has length: 2",
+        "\t#2 shortest path to node 4 has length: 3",
+    ],
+)
+
 cc_binary(
     name = "dag_multiple_shortest_paths_sequential",
     srcs = ["dag_multiple_shortest_paths_sequential.cc"],
@@ -389,6 +504,23 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_multiple_shortest_paths_sequential_test",
+    binary = ":dag_multiple_shortest_paths_sequential",
+    grep_lines = [
+        "\t#1 shortest path has length: 200",
+        "\t#2 shortest path has length: 202",
+        "\t#1 shortest path (2, 4) has length: 20",
+        "\t#2 shortest path (2, 4) has length: 102",
+        "\t#1 shortest path (8, 1) has length: 101",
+        "\t#2 shortest path (8, 1) has length: 108",
+        "\t#1 shortest path (3, 3) has length: 0",
+        "\t#2 shortest path (3, 3) has length: 112",
+        "\t#1 shortest path (0, 0) has length: 0",
+        "\t#2 shortest path (0, 0) has length: 111",
+    ],
+)
+
 cc_binary(
     name = "dag_simple_constrained_shortest_path",
     srcs = ["dag_simple_constrained_shortest_path.cc"],
@@ -400,6 +532,12 @@ cc_binary(
     ],
 )
 
+run_binary_test(
+    name = "dag_simple_constrained_shortest_path_test",
+    binary = ":dag_simple_constrained_shortest_path",
+    grep_lines = ["Constrained shortest path length: 4"],
+)
+
 cc_binary(
     name = "dag_constrained_shortest_path_sequential",
     srcs = ["dag_constrained_shortest_path_sequential.cc"],
@@ -410,3 +548,14 @@ cc_binary(
         "@abseil-cpp//absl/strings",
     ],
 )
+
+run_binary_test(
+    name = "dag_constrained_shortest_path_sequential_test",
+    binary = ":dag_constrained_shortest_path_sequential",
+    grep_lines = [
+        "Initial distance: 200",
+        "Distance_2_3: 1",
+        "Distance_8_1: 100",
+        "Distance_3_7: 100",
+    ],
+)
diff --git a/ortools/graph/samples/assignment_min_flow.cc b/ortools/graph/samples/assignment_min_flow.cc
index 4adcd67521..b89a67eb3a 100644
--- a/ortools/graph/samples/assignment_min_flow.cc
+++ b/ortools/graph/samples/assignment_min_flow.cc
@@ -15,10 +15,12 @@
 // [START import]
 #include <cstddef>
 #include <cstdint>
+#include <cstdlib>
 #include <vector>
 
 #include "absl/base/log_severity.h"
 #include "absl/log/globals.h"
+#include "absl/log/log.h"
 #include "ortools/base/init_google.h"
 #include "ortools/graph/min_cost_flow.h"
 // [END import]
diff --git a/ortools/graph/samples/balance_min_flow.cc b/ortools/graph/samples/balance_min_flow.cc
index f9b8ccc3b4..5802be30d0 100644
--- a/ortools/graph/samples/balance_min_flow.cc
+++ b/ortools/graph/samples/balance_min_flow.cc
@@ -15,10 +15,12 @@
 // [START import]
 #include <cstddef>
 #include <cstdint>
+#include <cstdlib>
 #include <vector>
 
 #include "absl/base/log_severity.h"
 #include "absl/log/globals.h"
+#include "absl/log/log.h"
 #include "ortools/base/init_google.h"
 #include "ortools/graph/min_cost_flow.h"
 // [END import]
diff --git a/ortools/graph/samples/simple_max_flow_program.cc b/ortools/graph/samples/simple_max_flow_program.cc
index a49028a799..fbcb46fda2 100644
--- a/ortools/graph/samples/simple_max_flow_program.cc
+++ b/ortools/graph/samples/simple_max_flow_program.cc
@@ -16,10 +16,12 @@
 // [START import]
 #include <cstddef>
 #include <cstdint>
+#include <cstdlib>
 #include <vector>
 
 #include "absl/base/log_severity.h"
 #include "absl/log/globals.h"
+#include "absl/log/log.h"
 #include "ortools/base/init_google.h"
 #include "ortools/graph/max_flow.h"
 // [END import]
diff --git a/ortools/graph/samples/simple_min_cost_flow_program.cc b/ortools/graph/samples/simple_min_cost_flow_program.cc
index 319123cf4e..611cadab2d 100644
--- a/ortools/graph/samples/simple_min_cost_flow_program.cc
+++ b/ortools/graph/samples/simple_min_cost_flow_program.cc
@@ -16,10 +16,12 @@
 // [START import]
 #include <cstddef>
 #include <cstdint>
+#include <cstdlib>
 #include <vector>
 
 #include "absl/base/log_severity.h"
 #include "absl/log/globals.h"
+#include "absl/log/log.h"
 #include "ortools/base/init_google.h"
 #include "ortools/graph/min_cost_flow.h"
 // [END import]
diff --git a/ortools/graph/strongly_connected_components.h b/ortools/graph/strongly_connected_components.h
index ecc616a5f5..bd92303f49 100644
--- a/ortools/graph/strongly_connected_components.h
+++ b/ortools/graph/strongly_connected_components.h
@@ -181,6 +181,9 @@ class StronglyConnectedComponentsFinder {
   bool NodeIsInCurrentDfsPath(NodeIndex node) const {
     return node_index_[node] > 0 && node_index_[node] < kSettledIndex;
   }
+  bool NodeIsNotYetExplored(NodeIndex node) const {
+    return node_index_[node] == 0;
+  }
 
  private:
   static constexpr NodeIndex kSettledIndex =