Kahn's algorithm
class Solution:
def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
indegree = [0] * numCourses
adj = [[] for x in range(numCourses)]
for prereq in prerequisites:
adj[prereq[1]].append(prereq[0])
indegree[prereq[0]] += 1
queue = []
for i in range(numCourses):
if indegree[i] == 0:
queue.append(i)
visited = 0
while queue:
node = queue.pop(0)
visited += 1
for neighbor in adj[node]:
indegree[neighbor] -= 1
if indegree[neighbor] == 0:
queue.append(neighbor)
return numCourses == visited