Implementing Depth-First Search (DFS) in Python

Implemented Depth-First Search (DFS) from Scratch in Python! DFS is one of the most fundamental graph traversal algorithms — think of it like navigating a maze: you pick a path and follow it all the way until you hit a dead end, then backtrack and try the next unexplored route. I implemented the iterative version using an explicit stack (preferred in production since it avoids Python's recursion depth limit). Here's how it works: 1. Push the start node onto a stack 2. Pop the top node (LIFO — last in, first out) 3. Visit all its unvisited neighbours and push them onto the stack 4. Repeat until the stack is empty Key takeaways: Time Complexity: O(V + E) — visits every vertex and edge once Space Complexity: O(V) — for the visited set + stack Used reversed() on neighbours so the traversal visits them in natural left-to-right order (since stack is LIFO, reversing ensures the first neighbour gets popped first) The stack is what makes this DFS — swap it with a queue and you get BFS! DFS vs BFS in one line: DFS goes deep before going wide (Stack / LIFO) BFS goes wide before going deep (Queue / FIFO) #Python #DataStructures #Algorithms #DFS #DepthFirstSearch #GraphAlgorithms #CodingJourney #DSA #Programming #SoftwareEngineering #LearningInPublic

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