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🧠 Interactive DFS Tutorial

Click on Run Example DFS to see the algorithm traversal. Start the Interactive DFS after the example has completed!

Click on the correct nodes that follow the DFS traversal path. Complete the traversal and test your knowledge with a quiz!

Answer each question correctly with the knowledge you've accumulated. Move on to the coding activity when complete!

Fill in the blanks and run the code. Hints will be available on submission.

def dfs(graph, start):
    visited = set()
    stack = []   # blank #1
    while stack:
        node = stack.pop()
        if node not in visited:
            visited.add(node)
            # push neighbors in reverse so left-most comes out first
            stack.extend()
    return visited

Depth-First Search (DFS) — Pseudocode

  procedure DFS(G, start):
    visited ← set()
    parent  ← map()
    time    ← 0

    function visit(u):
        visited.add(u)
        time ← time + 1
        for v in G.neighbors(u):
            if v ∉ visited:
                parent[v] ← u
                visit(v)
        time ← time + 1

    visit(start)
    return parent

  procedure DFS_iter(G, start):
    visited ← set()
    parent  ← map()
    S ← stack([start])

    while S not empty:
        u ← S.pop()
        if u ∉ visited:
            visited.add(u)
            for v in reverse(G.neighbors(u)):
                if v ∉ visited:
                    parent[v] ← u
                    S.push(v)
    return parent

Mentally trace the code to understand the algorithm's traversal pathing!

🧠 Interactive DFS Tutorial

🧩 Application: Solve a Maze with BFS / DFS / A*

🧩 Application: Solve a Maze with BFS / DFS / A*