solve: course schedule

Author: sounmind

course-schedule/evan.py

@@ -0,0 +1,34 @@
+from collections import defaultdict
+
+
+class Solution:
+    def canFinish(self, numCourses, prerequisites):
+        graph = defaultdict(list)
+
+        for course, prerequisite in prerequisites:
+            graph[course].append(prerequisite)
+
+        visit = ["unvisited"] * numCourses
+
+        def detectCycle(course):
+            if visit[course] == "visiting":
+                return True  # Cycle detected
+            if visit[course] == "visited":
+                return False  # Already fully visited
+
+            visit[course] = "visiting"  # Mark as visiting
+
+            for prerequisite in graph[course]:
+                if detectCycle(prerequisite):
+                    return True
+
+            visit[course] = "visited"  # Mark as fully visited
+
+            return False
+
+        # Perform cycle detection for all courses
+        for course in range(numCourses):
+            if detectCycle(course):
+                return False
+
+        return True