62 lines
1.2 KiB
Python
62 lines
1.2 KiB
Python
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# A dfs algorithm in Python
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# This is an algorithm for traversing a graph in depth first search manner
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# It is commonly used in tree/graph traversals
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# Time Complexity: O(V+E)
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# Space Complexity: O(V)
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# V is number of vertices and E is number of edges
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"""
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Refer the following example for output
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Graph 1: https://cdn.programiz.com/sites/tutorial2program/files/graph-dfs-step-0.png
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Graph 2: https://static.javatpoint.com/ds/images/depth-first-search-algorithm2.png
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"""
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def dfs(edges, vis, node):
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if(vis[node]!=1):
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vis[node] = 1
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print(node, end = " ")
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for i in edges[node]:
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if(vis[i]!=1):
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dfs(edges, vis, i)
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def main():
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""" Main Function """
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#First example
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graph1 = []
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graph1.append([1,2,3])
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graph1.append([0,2])
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graph1.append([0,1,4])
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graph1.append([0])
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graph1.append([2])
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vis = []
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for i in range(0,10):
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vis.append(0)
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print("DFS for Graph 1 is:")
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dfs(graph1, vis, 0)
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#Making visited list elements 0 for second graph
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for i in range(0,10):
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vis[i] = 0
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graph2 = []
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graph2.append([1, 2, 3])
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graph2.append([3])
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graph2.append([4])
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graph2.append([5, 6])
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graph2.append([5, 7])
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graph2.append([2])
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graph2.append([])
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graph2.append([])
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print("\n\nDFS for Graph 2 is:")
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dfs(graph2, vis, 0)
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if __name__=="__main__":
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main()
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