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Aya Bouchiha
Aya Bouchiha

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Depth First Search (DFS) Algorithm

Hi, today, we're going to talk about Depth First Search (DFS)

Definition of Depth First Search

  • Depth First Search: is an algorithm for traversing or searching in tree or graph data structure using recursion and Stack data structure.

Time & Space complexity of Depth First Search (DFS)

Space complexlity O(V)
Time complexity O(V+E)

Depth First Search applications

  • Counting connected components
  • Solving Sudoku Puzzles
  • Topological sorting
  • Pathfinding
  • Finding Strongly Connected Components of a graph

Depth First Search implementation in Python

more details...

# code from
graph = {
    'A' : ['B','C'],
    'B' : ['D', 'E'],
    'C' : ['F'],
    'D' : [],
    'E' : ['F'],
    'F' : []

visited = set() # Set to keep track of visited nodes.

def dfs(visited, graph, node):
    if node not in visited:
        for neighbour in graph[node]:
            dfs(visited, graph, neighbour)

dfs(visited, graph, 'A')
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References & useful Resources

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