depth-first traversal has been implemented

10.Iterators/src/depth-bypass.py

@@ -0,0 +1,85 @@
+class Graph:
+    def __init__(self):
+        self._adjacency_list = {}
+        self._start_vertex = None
+
+    def add_vertex(self, vertex):
+        if vertex not in self._adjacency_list:
+            self._adjacency_list[vertex] = []
+            if self._start_vertex is None:
+                self._start_vertex = vertex
+        return self
+
+    def add_edge(self, vertex1, vertex2):
+        self.add_vertex(vertex1)
+        self.add_vertex(vertex2)
+        if vertex2 not in self._adjacency_list[vertex1]:
+            self._adjacency_list[vertex1].append(vertex2)
+        if vertex1 not in self._adjacency_list[vertex2]:
+            self._adjacency_list[vertex2].append(vertex1)
+        return self
+
+    def set_start_vertex(self, vertex):
+        if vertex in self._adjacency_list:
+            self._start_vertex = vertex
+        return self
+
+    def dfs(self, start_vertex=None):
+        if not self._adjacency_list:
+            return []
+
+        if start_vertex is None:
+            start_vertex = self._start_vertex
+
+        if start_vertex not in self._adjacency_list:
+            raise ValueError(f"Вершина {start_vertex} не существует в графе")
+
+        visited = []
+        stack = [start_vertex]
+
+        while stack:
+            vertex = stack.pop()
+            if vertex not in visited:
+                visited.append(vertex)
+                for neighbor in reversed(self._adjacency_list.get(vertex, [])):
+                    if neighbor not in visited:
+                        stack.append(neighbor)
+
+        return visited
+
+    def __iter__(self):
+        self._dfs_visited = []
+        self._dfs_stack = []
+
+        if self._start_vertex and self._adjacency_list:
+            self._dfs_stack.append(self._start_vertex)
+
+        return self
+
+    def __next__(self):
+        while self._dfs_stack:
+            vertex = self._dfs_stack.pop()
+            if vertex not in self._dfs_visited:
+                self._dfs_visited.append(vertex)
+                for neighbor in reversed(self._adjacency_list.get(vertex, [])):
+                    if neighbor not in self._dfs_visited:
+                        self._dfs_stack.append(neighbor)
+                return vertex
+
+        for vertex in self._adjacency_list:
+            if vertex not in self._dfs_visited:
+                self._dfs_stack.append(vertex)
+                return self.__next__()
+
+        raise StopIteration
+
+
+if __name__ == "__main__":
+    g = Graph()
+    g.add_edge('A', 'B').add_edge('B', 'C').add_edge('A', 'D')
+
+    print("DFS обход от A:", g.dfs('A'))
+
+    print("Итерация по графу:")
+    for vertex in g:
+        print(vertex)