class Graph:

def __init__(self, v):

# No. of vertices of graph

self.v = v

# Adjacency List

self.adj = [0] * v

for i in range(self.v):

self.adj[i] = []

def addedge(self, i,j):

self.adj[i].append(j)

def isCyclic(self):

visited = [False] * self.v

helper = [False] * self.v

for i in range(self.v):

if visited[i] == False:

ans = self.DFS(i,visited,helper)

if ans == True:

return True

return False

def DFS(self,i, visited,helper):

visited[i] = True

helper[i] = True

neighbours = self.adj[i]

for k in range(len(neighbours)):

curr = neighbours[k]

if helper[curr] == True:

return True

if visited[curr] == False:

ans = self.DFS(curr,visited,helper)

if ans == True:

return True

helper[i] = False

return False

if __name__ == "__main__":

# No of nodes

n = 4

g = Graph(n)

g.addedge(0, 1)

g.addedge(3, 1)

g.addedge(1, 2)

g.addedge(0, 3)

if g.isCyclic() == 1:

print("Graph has a cycle")

else:

print("Graph has no cycle")