This notebook was prepared by Donne Martin. Source and license info is on GitHub.
Input:
add_edge(source, destination, weight)
graph.add_edge(0, 1, 5)
graph.add_edge(0, 4, 3)
graph.add_edge(0, 5, 2)
graph.add_edge(1, 3, 5)
graph.add_edge(1, 4, 4)
graph.add_edge(2, 1, 6)
graph.add_edge(3, 2, 7)
graph.add_edge(3, 4, 8)
Result:
If we want to visit every node in a graph, we generally prefer depth-first search since it is simpler (no need to use a queue). For shortest path, we generally use breadth-first search.
Complexity:
%run ../graph/graph.py
class GraphDfs(Graph):
def dfs(self, root, visit_func):
if root is None:
return
visit_func(root)
root.visit_state = State.visited
for node in root.adj_nodes.values():
if node.visit_state == State.unvisited:
self.dfs(node, visit_func)
%run ../utils/results.py
%%writefile test_dfs.py
import unittest
class TestDfs(unittest.TestCase):
def __init__(self, *args, **kwargs):
super(TestDfs, self).__init__()
self.results = Results()
def test_dfs(self):
nodes = []
graph = GraphDfs()
for id in range(0, 6):
nodes.append(graph.add_node(id))
graph.add_edge(0, 1, 5)
graph.add_edge(0, 4, 3)
graph.add_edge(0, 5, 2)
graph.add_edge(1, 3, 5)
graph.add_edge(1, 4, 4)
graph.add_edge(2, 1, 6)
graph.add_edge(3, 2, 7)
graph.add_edge(3, 4, 8)
graph.dfs(nodes[0], self.results.add_result)
self.assertEqual(str(self.results), "[0, 1, 3, 2, 4, 5]")
print('Success: test_dfs')
def main():
test = TestDfs()
test.test_dfs()
if __name__ == '__main__':
main()
Overwriting test_dfs.py
%run -i test_dfs.py
Success: test_dfs