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

# code from https://www.educative.io/edpresso/how-to-implement-depth-first-search-in-python
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:
        print(node)
        visited.add(node)
        for neighbour in graph[node]:
            dfs(visited, graph, neighbour)

dfs(visited, graph, 'A')