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* Adds Doc test in depth_first_search_2.py * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Fixes depth_first_search_2.py formatting * Cleanup --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
128 lines
3.2 KiB
Python
128 lines
3.2 KiB
Python
#!/usr/bin/python
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""" Author: OMKAR PATHAK """
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class Graph:
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def __init__(self):
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self.vertex = {}
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# for printing the Graph vertices
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def print_graph(self) -> None:
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"""
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Print the graph vertices.
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Example:
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>>> g = Graph()
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>>> g.add_edge(0, 1)
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>>> g.add_edge(0, 2)
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>>> g.add_edge(1, 2)
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>>> g.add_edge(2, 0)
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>>> g.add_edge(2, 3)
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>>> g.add_edge(3, 3)
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>>> g.print_graph()
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{0: [1, 2], 1: [2], 2: [0, 3], 3: [3]}
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0 -> 1 -> 2
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1 -> 2
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2 -> 0 -> 3
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3 -> 3
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"""
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print(self.vertex)
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for i in self.vertex:
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print(i, " -> ", " -> ".join([str(j) for j in self.vertex[i]]))
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# for adding the edge between two vertices
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def add_edge(self, from_vertex: int, to_vertex: int) -> None:
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"""
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Add an edge between two vertices.
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:param from_vertex: The source vertex.
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:param to_vertex: The destination vertex.
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Example:
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>>> g = Graph()
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>>> g.add_edge(0, 1)
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>>> g.add_edge(0, 2)
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>>> g.print_graph()
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{0: [1, 2]}
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0 -> 1 -> 2
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"""
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# check if vertex is already present,
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if from_vertex in self.vertex:
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self.vertex[from_vertex].append(to_vertex)
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else:
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# else make a new vertex
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self.vertex[from_vertex] = [to_vertex]
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def dfs(self) -> None:
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"""
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Perform depth-first search (DFS) traversal on the graph
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and print the visited vertices.
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Example:
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>>> g = Graph()
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>>> g.add_edge(0, 1)
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>>> g.add_edge(0, 2)
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>>> g.add_edge(1, 2)
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>>> g.add_edge(2, 0)
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>>> g.add_edge(2, 3)
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>>> g.add_edge(3, 3)
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>>> g.dfs()
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0 1 2 3
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"""
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# visited array for storing already visited nodes
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visited = [False] * len(self.vertex)
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# call the recursive helper function
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for i in range(len(self.vertex)):
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if not visited[i]:
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self.dfs_recursive(i, visited)
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def dfs_recursive(self, start_vertex: int, visited: list) -> None:
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"""
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Perform a recursive depth-first search (DFS) traversal on the graph.
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:param start_vertex: The starting vertex for the traversal.
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:param visited: A list to track visited vertices.
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Example:
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>>> g = Graph()
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>>> g.add_edge(0, 1)
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>>> g.add_edge(0, 2)
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>>> g.add_edge(1, 2)
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>>> g.add_edge(2, 0)
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>>> g.add_edge(2, 3)
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>>> g.add_edge(3, 3)
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>>> visited = [False] * len(g.vertex)
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>>> g.dfs_recursive(0, visited)
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0 1 2 3
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"""
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# mark start vertex as visited
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visited[start_vertex] = True
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print(start_vertex, end="")
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# Recur for all the vertices that are adjacent to this node
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for i in self.vertex:
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if not visited[i]:
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print(" ", end="")
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self.dfs_recursive(i, visited)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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g = Graph()
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g.add_edge(0, 1)
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g.add_edge(0, 2)
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g.add_edge(1, 2)
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g.add_edge(2, 0)
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g.add_edge(2, 3)
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g.add_edge(3, 3)
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g.print_graph()
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print("DFS:")
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g.dfs()
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