This notebook was prepared by Donne Martin. Source and license info is on GitHub.

# Challenge Notebook¶

## Constraints¶

• Is the graph directed?
• Yes
• Can we assume we already have Graph and Node classes?
• Yes
• Can we assume this is a connected graph?
• Yes
• Can we assume the inputs are valid?
• Yes
• Can we assume this fits memory?
• Yes

## Test Cases¶

Input:

• add_edge(source, destination, weight)
graph.add_edge(0, 1, 5)
graph.add_edge(3, 4, 8)

Result:

• search_path(start=0, end=2) -> True
• search_path(start=0, end=0) -> True
• search_path(start=4, end=5) -> False

## Algorithm¶

Refer to the Solution Notebook. If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start.

## Code¶

In [ ]:
%run ../graph/graph.py

In [ ]:
class GraphPathExists(Graph):

def path_exists(self, start, end):
# TODO: Implement me
pass


## Unit Test¶

The following unit test is expected to fail until you solve the challenge.

In [ ]:
# %load test_path_exists.py
import unittest

class TestPathExists(unittest.TestCase):

def test_path_exists(self):
nodes = []
graph = GraphPathExists()
for id in range(0, 6):

self.assertEqual(graph.path_exists(nodes[0], nodes[2]), True)
self.assertEqual(graph.path_exists(nodes[0], nodes[0]), True)
self.assertEqual(graph.path_exists(nodes[4], nodes[5]), False)

print('Success: test_path_exists')

def main():
test = TestPathExists()
test.test_path_exists()

if __name__ == '__main__':
main()


## Solution Notebook¶

Review the Solution Notebook for a discussion on algorithms and code solutions.