Python/graphs/kahns_algorithm_long.py
Christian Clauss 1f8a21d727
Tighten up psf/black and flake8 (#2024)
* Tighten up psf/black and flake8

* Fix some tests

* Fix some E741

* Fix some E741

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-05-22 08:10:11 +02:00

32 lines
806 B
Python

# Finding longest distance in Directed Acyclic Graph using KahnsAlgorithm
def longestDistance(graph):
indegree = [0] * len(graph)
queue = []
longDist = [1] * len(graph)
for key, values in graph.items():
for i in values:
indegree[i] += 1
for i in range(len(indegree)):
if indegree[i] == 0:
queue.append(i)
while queue:
vertex = queue.pop(0)
for x in graph[vertex]:
indegree[x] -= 1
if longDist[vertex] + 1 > longDist[x]:
longDist[x] = longDist[vertex] + 1
if indegree[x] == 0:
queue.append(x)
print(max(longDist))
# Adjacency list of Graph
graph = {0: [2, 3, 4], 1: [2, 7], 2: [5], 3: [5, 7], 4: [7], 5: [6], 6: [7], 7: []}
longestDistance(graph)