Create 1462-course-schedule-iv.py

Author: neetcode-gh

python/1462-course-schedule-iv.py

@@ -0,0 +1,22 @@
+class Solution:
+    def checkIfPrerequisite(self, numCourses: int, prerequisites: List[List[int]], queries: List[List[int]]) -> List[bool]:
+        adj = defaultdict(list)
+        for prereq, crs in prerequisites:
+            adj[crs].append(prereq)
+        
+        def dfs(crs):
+            if crs not in prereqMap:
+                prereqMap[crs] = set()
+                for pre in adj[crs]:
+                    prereqMap[crs] |= dfs(pre)
+            prereqMap[crs].add(crs)
+            return prereqMap[crs]
+
+        prereqMap = {} # map course -> set indirect prereqs
+        for crs in range(numCourses):
+            dfs(crs)
+
+        res = []
+        for u, v in queries:
+            res.append(u in prereqMap[v])
+        return res