@pC thanks a lot for your answer and efforts. I have few doubts regrading the way you are implementing the Algorithm -
1. You are marking the node as visited and then pushing it onto the stack.
2. You are checking if the nodes is unvisited and only then are you pushing onto the stack by marking it as visited.
Your algorithm will ensure that there will never be any node that is pushed onto the stack more than once isnt it?
Kindly have a look at this algorithm from stackoverflow where all the adjacent nodes are pushed onto the stack and marked as visited during the pop operation. In the below algorithm every node will be pushed at least twice. Because even the parent who discovered a node will be added..
DFS(source):
s <- new stack
visited <- {} // empty set
s.push(source)
while (s is not empty):
current <- s.pop()
if (current is in visited):
continue
visited.add(current)
// do something with current
for each node v such that (current,v) is an edge:
s.push(v)
