Add typing to topological_sort.py (#9650)

* Add typing

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: Jeremy Tan <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

Diff for: sorts/topological_sort.py

@@ -5,11 +5,17 @@
 #   b  c
 #  / \
 # d  e
-edges = {"a": ["c", "b"], "b": ["d", "e"], "c": [], "d": [], "e": []}
-vertices = ["a", "b", "c", "d", "e"]
+edges: dict[str, list[str]] = {
+    "a": ["c", "b"],
+    "b": ["d", "e"],
+    "c": [],
+    "d": [],
+    "e": [],
+}
+vertices: list[str] = ["a", "b", "c", "d", "e"]
 
 
-def topological_sort(start, visited, sort):
+def topological_sort(start: str, visited: list[str], sort: list[str]) -> list[str]:
     """Perform topological sort on a directed acyclic graph."""
     current = start
     # add current to visited