solve : course schedule

Author: SamTheKorean

course-schedule/samthekorean.py

@@ -0,0 +1,34 @@
+# V is number of verticles and E is number of edges
+# TC : O(V+E)
+# SC : O(V+E)
+class Solution:
+    def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
+
+        pre = defaultdict(list)
+
+        for course, p in prerequisites:
+            pre[course].append(p)
+
+        taken = set()
+
+        def dfs(course):
+            if not pre[course]:
+                return True
+
+            if course in taken:
+                return False
+
+            taken.add(course)
+
+            for p in pre[course]:
+                if not dfs(p):
+                    return False
+
+            pre[course] = []
+            return True
+
+        for course in range(numCourses):
+            if not dfs(course):
+                return False
+
+        return True