How do I implement BFS and DFS algorithms in Python?

How do I implement BFS and DFS algorithms in Python?

To implement BFS (Breadth-First Search) and DFS (Depth-First Search) in Python, you can use a graph represented as an adjacency list. Would you like to see code examples for both?

Yes, please show me the code for both algorithms.

Sure! Here's a simple implementation:

from collections import deque

# BFS implementation

def bfs(graph, start):
    visited = set()
    queue = deque([start])
    while queue:
        vertex = queue.popleft()
        if vertex not in visited:
            visited.add(vertex)
            queue.extend(neighbor for neighbor in graph[vertex] if neighbor not in visited)
    return visited

# DFS implementation

def dfs(graph, start, visited=None):
    if visited is None:
        visited = set()
    visited.add(start)
    for neighbor in graph[start]:
        if neighbor not in visited:
            dfs(graph, neighbor, visited)
    return visited

Would you like to know how to use these functions with a sample graph?

Yes, that would be great!

Here's how you can use the BFS and DFS functions with a sample graph:

# Sample graph as an adjacency list
graph = {
    'A': ['B', 'C'],
    'B': ['A', 'D', 'E'],
    'C': ['A', 'F'],
    'D': ['B'],
    'E': ['B', 'F'],
    'F': ['C', 'E']
}

# Using BFS
print(bfs(graph, 'A'))  # Output: {'A', 'B', 'C', 'D', 'E', 'F'}

# Using DFS
print(dfs(graph, 'A'))  # Output: {'A', 'B', 'D', 'E', 'F', 'C'}

This will give you the order of traversal for both algorithms. Let me know if you have any questions!