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Commit 1c37692

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Add Dijkstra's algorithm implementation
1 parent 25d71ff commit 1c37692

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+85
-16
lines changed

6 files changed

+85
-16
lines changed

‎.gitignore‎

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graphs_in_python_lessions/representing_graphs_in_code/base_classes/__pycache__
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graphs_in_python_lessions/representing_graphs_in_code/__pycache__
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__pycache__/
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*.py[cod]
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*$py.class
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from queue import PriorityQueue
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class Graph:
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def __init__(self, num_of_vertices):
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self.v = num_of_vertices
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self.edges = [[-1 for i in range(num_of_vertices)] for j in range(num_of_vertices)]
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self.visited = []
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def add_edge(self, u, v, weight):
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self.edges[u][v] = weight
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self.edges[v][u] = weight
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def dijkstra(self, start_vertex):
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D = {v:float('inf') for v in range(self.v)}
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D[start_vertex] = 0
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pq = PriorityQueue()
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pq.put((0, start_vertex))
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while not pq.empty():
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(dist, current_vertex) = pq.get()
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self.visited.append(current_vertex)
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for neighbor in range(self.v):
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if self.edges[current_vertex][neighbor] != -1:
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distance = self.edges[current_vertex][neighbor]
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if neighbor not in self.visited:
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old_cost = D[neighbor]
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new_cost = D[current_vertex] + distance
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if new_cost < old_cost:
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pq.put((new_cost, neighbor))
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D[neighbor] = new_cost
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return D
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def main():
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g = Graph(9)
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g.add_edge(0, 1, 4)
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g.add_edge(0, 6, 7)
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g.add_edge(1, 6, 11)
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g.add_edge(1, 7, 20)
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g.add_edge(1, 2, 9)
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g.add_edge(2, 3, 6)
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g.add_edge(2, 4, 2)
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g.add_edge(3, 4, 10)
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g.add_edge(3, 5, 5)
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g.add_edge(4, 5, 15)
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g.add_edge(4, 7, 1)
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g.add_edge(4, 8, 5)
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g.add_edge(5, 8, 12)
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g.add_edge(6, 7, 1)
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g.add_edge(7, 8, 3)
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D = g.dijkstra(0)
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print(D)
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for vertex in range(len(D)):
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print("Distance from vertex 0 to vertex", vertex, "is", D[vertex])
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if __name__=="__main__":
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main()

‎structure.md‎

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### Repo Structure
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##Graphs in Python Repo Structure
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- base_classes
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- `node.py`
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- `graph.py`
@@ -8,18 +8,25 @@
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- `adj_matrix_graph.py`
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- `adj_list_graph.py`
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- lessions
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- representing_graphs_in_code
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- base_classes
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- `node.py`
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- `graph.py`
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- `edge_list_graph.py`
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- `adj_matrix_graph.py`
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- `adj_list_graph.py`
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- `test.py`
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- depth_first_search
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- breadth_first_search
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- dijkstra
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- graphs_in_python_lessions
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- 01_representing_graphs_in_code
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- advanced_implementations
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- base_classes
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- `node.py`
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- `graph.py`
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- `edge_list_graph.py`
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- `adj_matrix_graph.py`
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- `adj_list_graph.py`
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- `test.py`
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- `edge_list_graph_basic.py`
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- `adj_matrix_graph_basic.py`
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- `adj_list_graph_basic.py`
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- 02_depth_first_search
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- `dfs.py`
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- 03_breadth_first_search
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- `bfs.py`
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- 04_dijkstra
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- `dijkstra.py`
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- a*
2431
- mst_boruvka
2532
- mst_kruskal

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