day 92: return nil for partitioned DAG

vaskoz · Nov 23, 2018 · e162756 · e162756
1 parent d77fa04
commit e162756
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Showing 2 changed files with 16 additions and 3 deletions.
diff --git a/day92/problem.go b/day92/problem.go
@@ -14,6 +14,9 @@ func CourseOrder(prereq map[string][]string) []string {
 			}
 		}
 	}
+	if len(marked) != len(prereq) {
+		return nil
+	}
 	reverse(result)
 	return result
 }

diff --git a/day92/problem_test.go b/day92/problem_test.go
@@ -10,11 +10,21 @@ var testcases = []struct {
 	expected []string
 }{
 	{map[string][]string{
-		"CSC300": []string{"CSC100", "CSC200"},
-		"CSC200": []string{"CSC100"},
-		"CSC100": []string{},
+		"CSC300": {"CSC100", "CSC200"},
+		"CSC200": {"CSC100"},
+		"CSC100": {},
 	},
 		[]string{"CSC100", "CSC200", "CSC300"}},
+	{map[string][]string{
+		"CSC300": {"CSC100"},
+		"CSC100": {"CSC300"},
+	},
+		[]string{"CSC100", "CSC300"}},
+	{map[string][]string{
+		"CSC300": {"CSC100"},
+		"CSC400": {"CSC200"},
+	},
+		nil},
 }
 
 func TestCourseOrder(t *testing.T) {