From 1258c4ef3e08ac99fe3746454ef79bb5f9b415c5 Mon Sep 17 00:00:00 2001
From: ermmmaks <maks.ermoshkin56@gmail.com>
Date: Fri, 28 Nov 2025 17:40:41 +0300
Subject: [PATCH 1/2] Add dfs algotithm

---
 src/dfs.py | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 src/dfs.py

diff --git a/src/dfs.py b/src/dfs.py
new file mode 100644
index 0000000..e66cf61
--- /dev/null
+++ b/src/dfs.py
@@ -0,0 +1,35 @@
+class Graph:
+    def __init__(self, vertices: list[int], edges: list[tuple[int, int]]):
+        self.vertices = vertices
+        self.edges = edges
+        self.passage= []
+    
+    def __iter__(self):
+        if not self.passage:
+            self.dfs()
+        return iter(self.passage)
+
+    def dfs(self):
+        passed = set()
+        self.passage = []
+
+        def step(vertex):
+            if vertex not in passed:
+                passed.add(vertex)
+                self.passage.append(vertex)
+
+                neighbors = []
+                for edge in self.edges:
+                    if edge[0] == vertex:
+                        neighbors.append(edge[1])
+                    elif edge[1] == vertex:
+                        neighbors.append(edge[0])
+                    
+                    for neighbor in neighbors:
+                        step(neighbor)
+
+        for vertex in self.vertices:
+            if vertex not in passed:
+                step(vertex)
+
+        return self.passage

From 9664c628bcde3e19aa00b69922bdfec8518a47cf Mon Sep 17 00:00:00 2001
From: ermmmaks <maks.ermoshkin56@gmail.com>
Date: Sat, 29 Nov 2025 00:47:02 +0300
Subject: [PATCH 2/2] Add tests for dfs

---
 src/dfs.py       |  4 ++--
 test/dfs_test.py | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 test/dfs_test.py

diff --git a/src/dfs.py b/src/dfs.py
index e66cf61..0d3de98 100644
--- a/src/dfs.py
+++ b/src/dfs.py
@@ -25,8 +25,8 @@ def step(vertex):
                     elif edge[1] == vertex:
                         neighbors.append(edge[0])
                     
-                    for neighbor in neighbors:
-                        step(neighbor)
+                for neighbor in neighbors:
+                    step(neighbor)
 
         for vertex in self.vertices:
             if vertex not in passed:
diff --git a/test/dfs_test.py b/test/dfs_test.py
new file mode 100644
index 0000000..d64d458
--- /dev/null
+++ b/test/dfs_test.py
@@ -0,0 +1,22 @@
+from src.dfs import Graph
+
+def test_simple_graph():
+    vertices = [1, 2, 3, 4]
+    edges = [(1, 2), (2, 3), (3, 4)]
+    graph = Graph(vertices, edges)
+    result = list(graph)
+    assert result == [1, 2, 3, 4]
+
+def test_single_vertex():
+    vertices = [1]
+    edges = []
+    graph = Graph(vertices, edges)
+    result = list(graph)
+    assert result == [1]
+
+def test_empty_graph():
+    vertices = []
+    edges = []
+    graph = Graph(vertices, edges)
+    result = list(graph)
+    assert result == []
\ No newline at end of file