Depth first traversal
DFS algorithm A standard DFS implementation puts each vertex of the graph into one of two categories: Visited Not Visited The purpose of the algorithm is to mark each vertex as visited while avoiding cycles. The DFS algorithm works as follows: Start by putting any one of the graph's vertices on top of a stack. Take the top item of the stack and add it to the visited list. Create a list of that vertex's adjacent nodes. Add the ones which aren't in the visited list to the top of stack. Keep repeating steps 2 and 3 until the stack is empty. DFS example Let's see how the Depth First Search algorithm works with an example. We use an undirected graph with 5 vertices. 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. 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.