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OUT LINE
Definition.
Strategies.
Algorithmic Steps.
Example.
Advantages and Disadvantages.
Definition
• Depth-first search (DFS) is an algorithm for traversing
or searching tree or graph data structures. The
algorithm starts at the root node (selecting some
arbitrary node as the root node in the case of a graph)
and explores as far as possible along each branch
before backtracking.
Algorithmic Steps
Strategies
Depth-first search (DFS) is three
popular Strategies.
•Pre-Order: Root->Left->Right.
•In-Order:
Left->Root->Right.
•Post-Oder: Left->Right->Root.
Example:
• Depth First Search ExampleLet's see how the Depth First Search
algorithm works with an example. We use an undirected graph
with 5 vertices.
Example:
• We start from vertex 0, the DFS algorithm starts by putting it in the
Visited list and putting all its adjacent vertices in the stack.
Example:
• Next, we visit the element at the top of stack i.e. 1 and go to its
adjacent nodes. Since 0 has already been visited, we visit 2 instead.
Example:
• Vertex 2 has an unvisited adjacent vertex in 4, so we add that to the
top of the stack and visit it.
Example:
Example:
• After we visit the last element 3, it doesn't have any unvisited
adjacent nodes, so we have completed the Depth First Traversal of
the graph.
Advantages and Disadvantages
• Advantages Of DFS:
1. The memory requirement is Linear WRT Nodes.
2. Less time and space complexity rather than BFS.
3. The solution can be found out without much more search.
• The disadvantage of DFS:
1. Not Guaranteed that it will give you a solution.
2. Cut-off depth is smaller so time complexity is more.
3. Determination of depth until the search has proceeded.
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