feat: 1466. Reorder Routes to Make All Paths Lead to the City Zero

src/graphs/reorder_routes_to_make_all_paths_lead_to_the_city_zero/solution.py

@@ -0,0 +1,24 @@
+class Solution:
+    def dfs(
+        self,
+        adjacent: list[list[tuple[int, int]]],
+        visited: list[bool],
+        current_city: int,
+    ) -> int:
+        visited[current_city] = True
+        changes = 0
+        for neighbour, direction in adjacent[current_city]:
+            if not visited[neighbour]:
+                if direction == 1:
+                    changes += 1
+                changes += self.dfs(adjacent, visited, neighbour)
+
+        return changes
+
+    def minReorder(self, n: int, connections: list[list[int]]) -> int:
+        adjacent = [[] for _ in range(n)]
+        for u, v in connections:
+            adjacent[u].append((v, 1))
+            adjacent[v].append((u, -1))
+        visited = [False] * n
+        return self.dfs(adjacent, visited, 0)

tests/test_reorder_routes_to_make_all_paths_lead_to_the_city_zero.py

@@ -0,0 +1,17 @@
+import pytest
+from src.graphs.reorder_routes_to_make_all_paths_lead_to_the_city_zero.solution import (
+    Solution,
+)
+
+
+@pytest.mark.parametrize(
+    "n, connections, expected",
+    [
+        (6, [[0, 1], [1, 3], [2, 3], [4, 0], [4, 5]], 3),
+        (5, [[1, 0], [1, 2], [3, 2], [3, 4]], 2),
+        (3, [[1, 0], [2, 0]], 0),
+    ],
+)
+def test_min_reorder(n, connections, expected):
+    solution = Solution()
+    assert solution.minReorder(n, connections) == expected