Detect Cycle in Directed Graph(Kanh's algorithm)

'''
Acyclic directed graph is needed for the toplogical sort ie. DAG
you can apply the topo sort on it and if the topo sort is having the same number of
the vertices in the graph, it means no cycle else there is the cycle.
You need not to store the full topo sort order, you can store the count also when indegree ==0

If cycle exists, there will be some node whose indegree will never be 0 so it will not pushed to the deque and because of that the vertices connecting them will not be processed.
'''
from collections import deque, defaultdict
class Solution:
    def isCyclic(self, v, edges):
        graph=defaultdict(list)
        indegree=[0]*v
        for a,b in edges:
            graph[a].append(b)
            indegree[b]+=1
        cnt=0
        q=deque([])
        for i in range(v):
            if indegree[i]==0:
                q.append(i)
                cnt+=1

        while q:
            k=len(q)
            for i in range(k):
                temp=q.popleft()
                # cnt+=1

                for neigh in graph[temp]:
                    indegree[neigh]-=1
                    if indegree[neigh]==0:
                        q.append(neigh)
                        cnt+=1
        if cnt!=v:
            return True
        else:
            return False