Python/graphs/kahns_algorithm_topo.py

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def topologicalSort(graph):
"""
Kahn's Algorithm is used to find Topological ordering of Directed Acyclic Graph
using BFS
"""
indegree = [0] * len(graph)
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queue = []
topo = []
cnt = 0
for key, values in graph.items():
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for i in values:
indegree[i] += 1
for i in range(len(indegree)):
if indegree[i] == 0:
queue.append(i)
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while queue:
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vertex = queue.pop(0)
cnt += 1
topo.append(vertex)
for x in graph[vertex]:
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indegree[x] -= 1
if indegree[x] == 0:
queue.append(x)
if cnt != len(graph):
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print("Cycle exists")
else:
print(topo)
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# Adjacency List of Graph
graph = {0: [1, 2], 1: [3], 2: [3], 3: [4, 5], 4: [], 5: []}
topologicalSort(graph)