From c53f37ab4334064114691cf571d62e3539ba421c Mon Sep 17 00:00:00 2001
From: Prakhar Bhatnagar <42675093+prakharb10@users.noreply.github.com>
Date: Sun, 29 Oct 2023 17:26:31 -0700
Subject: [PATCH] fix `all_simple_paths` (#1015)

* fix `min_depth=0` in `all_simple_paths`
Fixes #955

* added reno
---
 ...fix-all-simple-paths-03f4534438d1068d.yaml |  7 +++
 src/connectivity/mod.rs                       |  6 +-
 .../digraph/test_all_simple_paths.py          | 19 +++++++
 .../graph/test_all_simple_paths.py            | 55 +++++++++++++++++++
 4 files changed, 84 insertions(+), 3 deletions(-)
 create mode 100644 releasenotes/notes/fix-all-simple-paths-03f4534438d1068d.yaml

diff --git a/releasenotes/notes/fix-all-simple-paths-03f4534438d1068d.yaml b/releasenotes/notes/fix-all-simple-paths-03f4534438d1068d.yaml
new file mode 100644
index 000000000..e56393348
--- /dev/null
+++ b/releasenotes/notes/fix-all-simple-paths-03f4534438d1068d.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed the behavior of :func:`~rustworkx.graph_all_simple_paths` and
+    :func:`~rustworkx.digraph_all_simple_paths` when ``min_depth`` is set to
+    ``0``. Refer to `#955 <https://github.com/Qiskit/rustworkx/issues/955>`__ for
+    more information.
diff --git a/src/connectivity/mod.rs b/src/connectivity/mod.rs
index 11c49c951..ad900535a 100644
--- a/src/connectivity/mod.rs
+++ b/src/connectivity/mod.rs
@@ -548,8 +548,8 @@ pub fn graph_all_simple_paths(
         ));
     }
     let min_intermediate_nodes: usize = match min_depth {
+        Some(0) | None => 0,
         Some(depth) => depth - 2,
-        None => 0,
     };
     let cutoff_petgraph: Option<usize> = cutoff.map(|depth| depth - 2);
     let result: Vec<Vec<usize>> = algo::all_simple_paths(
@@ -573,7 +573,7 @@ pub fn graph_all_simple_paths(
 /// :param int to: The node index to find the paths to
 /// :param int min_depth: The minimum depth of the path to include in the output
 ///     list of paths. By default all paths are included regardless of depth,
-///     sett to 0 will behave like the default.
+///     setting to 0 will behave like the default.
 /// :param int cutoff: The maximum depth of path to include in the output list
 ///     of paths. By default includes all paths regardless of depth, setting to
 ///     0 will behave like default.
@@ -602,8 +602,8 @@ pub fn digraph_all_simple_paths(
         ));
     }
     let min_intermediate_nodes: usize = match min_depth {
+        Some(0) | None => 0,
         Some(depth) => depth - 2,
-        None => 0,
     };
     let cutoff_petgraph: Option<usize> = cutoff.map(|depth| depth - 2);
     let result: Vec<Vec<usize>> = algo::all_simple_paths(
diff --git a/tests/rustworkx_tests/digraph/test_all_simple_paths.py b/tests/rustworkx_tests/digraph/test_all_simple_paths.py
index c63ea2c41..3ee4ed54b 100644
--- a/tests/rustworkx_tests/digraph/test_all_simple_paths.py
+++ b/tests/rustworkx_tests/digraph/test_all_simple_paths.py
@@ -53,6 +53,25 @@ def test_all_simple_paths(self):
         for i in expected:
             self.assertIn(i, paths)
 
+    def test_all_simple_paths_default_min_depth(self):
+        dag = rustworkx.PyDAG()
+        for i in range(6):
+            dag.add_node(i)
+        dag.add_edges_from_no_data(self.edges)
+        paths = rustworkx.digraph_all_simple_paths(dag, 0, 5, min_depth=0)
+        expected = [
+            [0, 1, 2, 3, 4, 5],
+            [0, 1, 2, 4, 5],
+            [0, 1, 3, 2, 4, 5],
+            [0, 1, 3, 4, 5],
+            [0, 2, 3, 4, 5],
+            [0, 2, 4, 5],
+            [0, 3, 2, 4, 5],
+            [0, 3, 4, 5],
+        ]
+        for i in expected:
+            self.assertIn(i, paths)
+
     def test_all_simple_paths_min_depth(self):
         dag = rustworkx.PyDAG()
         for i in range(6):
diff --git a/tests/rustworkx_tests/graph/test_all_simple_paths.py b/tests/rustworkx_tests/graph/test_all_simple_paths.py
index b179be29a..9e0ad998f 100644
--- a/tests/rustworkx_tests/graph/test_all_simple_paths.py
+++ b/tests/rustworkx_tests/graph/test_all_simple_paths.py
@@ -89,6 +89,61 @@ def test_all_simple_paths(self):
         for i in expected:
             self.assertIn(i, paths)
 
+    def test_all_simple_paths_default_min_depth(self):
+        graph = rustworkx.PyGraph()
+        for i in range(6):
+            graph.add_node(i)
+        graph.add_edges_from_no_data(self.edges)
+        paths = rustworkx.graph_all_simple_paths(graph, 0, 5, min_depth=0)
+        expected = [
+            [0, 3, 4, 5],
+            [0, 3, 4, 2, 5],
+            [0, 3, 4, 2, 5],
+            [0, 3, 2, 4, 5],
+            [0, 3, 2, 5],
+            [0, 3, 2, 4, 5],
+            [0, 3, 5],
+            [0, 3, 2, 4, 5],
+            [0, 3, 2, 5],
+            [0, 3, 2, 4, 5],
+            [0, 3, 1, 2, 4, 5],
+            [0, 3, 1, 2, 5],
+            [0, 3, 1, 2, 4, 5],
+            [0, 2, 4, 5],
+            [0, 2, 4, 3, 5],
+            [0, 2, 3, 4, 5],
+            [0, 2, 3, 5],
+            [0, 2, 5],
+            [0, 2, 4, 5],
+            [0, 2, 4, 3, 5],
+            [0, 2, 3, 4, 5],
+            [0, 2, 3, 5],
+            [0, 2, 1, 3, 4, 5],
+            [0, 2, 1, 3, 5],
+            [0, 1, 3, 4, 5],
+            [0, 1, 3, 4, 2, 5],
+            [0, 1, 3, 4, 2, 5],
+            [0, 1, 3, 2, 4, 5],
+            [0, 1, 3, 2, 5],
+            [0, 1, 3, 2, 4, 5],
+            [0, 1, 3, 5],
+            [0, 1, 3, 2, 4, 5],
+            [0, 1, 3, 2, 5],
+            [0, 1, 3, 2, 4, 5],
+            [0, 1, 2, 4, 5],
+            [0, 1, 2, 4, 3, 5],
+            [0, 1, 2, 3, 4, 5],
+            [0, 1, 2, 3, 5],
+            [0, 1, 2, 5],
+            [0, 1, 2, 4, 5],
+            [0, 1, 2, 4, 3, 5],
+            [0, 1, 2, 3, 4, 5],
+            [0, 1, 2, 3, 5],
+        ]
+        self.assertEqual(len(expected), len(paths))
+        for i in expected:
+            self.assertIn(i, paths)
+
     def test_all_simple_paths_with_min_depth(self):
         graph = rustworkx.PyGraph()
         for i in range(6):