Hello, this is #day_29, I'm going to talk about Dijkstra's shortest path algorithm
Definition of Dijkstra's shortest path algorithm
dijkstra's shortest path is an algorithm created by Dr. Edsger Dijkstra for calculating the shortest path between vertices in a weighted graph (types of graph)
Example of a weighted graph
Dijkstra's shortest path applications
- Road networks
- Electricity lines
- Google maps
- Social networking apps
- Flighting agenda
- Ip routing more details
Dijkstra's shortest path implementation in python
If you are not familiar with Python check this series by @aatmaj
def dijkstraShortestPathAlgo(nodes, edges, source_indedx = 0):
"""
code from
=> [https://www.youtube.com/watch?v=VnTlW572Sc4]
"""
path_lengths = {v:float('inf') for v in nodes}
path_lengths[source_index] = 0
adjacent_nodes = {v:{} for v in nodes}
for (u, v), w_uv in edges.items():
adjacent_nodes[u][v] = w_uv
adjacent_nodes[v][u] = w_uv
temporary_nodes = [v for v in nodes]
while len(temporary_nodes) > 0:
upper_bounds = {v: path_lengths[v] for v in temporary_nodes}
u = min(upper_bounds, key=upper_bounds.get)
temporary_nodes.remove(u)
for v, w_uv in adjacent_nodes[u].items():
path_lengths[v] = min(path_lengths[v], path_lengths[u] + w_uv)
return path_lengths
References & useful resources
- https://www.geeksforgeeks.org/dijkstras-shortest-path-algorithm-greedy-algo-7/
- https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm
- https://www.freecodecamp.org/news/dijkstras-shortest-path-algorithm-visual-introduction/
- https://www.youtube.com/watch?v=smHnz2RHJBY
Happy coding!!
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