TheAlgorithms · ShengLiuDev · Feb 12, 2024 · Feb 12, 2024 · Feb 12, 2024 · Feb 12, 2024
diff --git a/sorts/topological_sort.py b/sorts/topological_sort.py
@@ -1,5 +1,7 @@
 """Topological Sort."""
 
+# Test cases:
+
 #     a
 #    / \
 #   b  c
@@ -15,27 +17,67 @@
 vertices: list[str] = ["a", "b", "c", "d", "e"]
 
 
-def topological_sort(start: str, visited: list[str], sort: list[str]) -> list[str]:
-    """Perform topological sort on a directed acyclic graph."""
+def topological_sort_util(
+    start: str, edges: dict[str, list[str]], visited: list[str], sort: list[str]
+) -> list[str]:
+    """"""
+    """
+    Examples:
+    >>> topological_sort(['a', 'b', 'c', 'd'], {"a": ["b", "c"], "b": ["d"],
+    "c": [], "d": []})
+    ['d', 'c', 'b', 'a']
+    >>> topological_sort(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'], {"a": ["b"],
+    "b": ["c"], "c": ["d"], "d": ["e"], "e": ["f"], "f": ["g"], "g": ["h"], "h": []})
+    ['h', 'g', 'f', 'e', 'd', 'c', 'b', 'a']
+    >>> topological_sort(['a', 'b', 'c', 'd', 'e', 'f', 'g'], {"a": ["b", "c"],
+    "b": ["d", "e"], "c": ["f", "g"], "d": [], "f": [], "h": []})
+    ['d', 'f', 'e', 'g', 'c', 'b', 'a']
+    >>> topological_sort([], {})
+    ['']
+    """
+
     current = start
     # add current to visited
     visited.append(current)
     neighbors = edges[current]
     for neighbor in neighbors:
         # if neighbor not in visited, visit
         if neighbor not in visited:
-            sort = topological_sort(neighbor, visited, sort)
+            sort = topological_sort_util(neighbor, edges, visited, sort)
     # if all neighbors visited add current to sort
     sort.append(current)
     # if all vertices haven't been visited select a new one to visit
-    if len(visited) != len(vertices):
-        for vertice in vertices:
-            if vertice not in visited:
-                sort = topological_sort(vertice, visited, sort)
+    if len(visited) != len(edges):
+        for vertex in edges:
+            if vertex not in visited:
+                sort = topological_sort_util(vertex, edges, visited, sort)
     # return sort
     return sort
 
 
+def topological_sort(vertices: list[str], edges: dict[str, list[str]]) -> list[str]:
+    sort: list[str] = []
+    visited: list[str] = []
+    for vertex in vertices:
+        if vertex not in visited:
+            sort = topological_sort_util(vertex, edges, visited, sort)
+    return sort
+
+
 if __name__ == "__main__":
-    sort = topological_sort("a", [], [])
+    # Get vertices from the user
+    vertices_input = input("Please enter the vertices separated by commas: ").strip()
+    vertices = [vertex.strip() for vertex in vertices_input.split(",")]
+    # Initialize an empty dictionary for edges
+    edges = {}
+    # Iterate over each vertex to get its connected edges
+    for vertex in vertices:
+        edges_input = input(
+            f'Please enter the edges connected to vertex "{vertex}" '
+            "separated by commas (leave empty to finish): "
+        ).strip()
+        edges[vertex] = [
+            edge.strip() for edge in edges_input.split(",") if edge.strip()
+        ]
+    sort = topological_sort(vertices, edges)
     print(sort)