Are recursion and a stack equivalent in terms of inplementing DFS?

Question

It is well known that DFS can be implemented either with recursion or a stack, and that both approaches are equivalent, but how far can we take that statement? Consider the following LeetCode problem:

Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1, find all possible paths from node 0 to node n - 1 and return them in any order.

The graph is given as follows: graph[i] is a list of all nodes you can visit from node i (i.e., there is a directed edge from node i to node graph[i][j]).

Here is a solution which uses DFS and maintains the current path in the graph with a stack stk.

def allPathsSourceTarget(graph: List[List[int]]) -> List[List[int]]:
    ans = list()
    stk = list()
def dfs(x: int):
    if x == len(graph) - 1:
        ans.append(stk[:])  # stk[:] returns a copy of stk
        return

    for y in graph[x]:
        stk.append(y)
        dfs(y)
        stk.pop()

stk.append(0)
dfs(0)
return ans

If recursion and stacks are equivalent, then there must exist an iterative solution that uses two stacks, one to implement DFS and another to maintain the current path (same purpose as stk). However, I'm struggling to come up with one. The trick park is maintaining stk. When using recursion, stk is simply the call stack, but that's no longer true with an explicit stack, because nodes from different branches may co-exist in it.

Question: how to write an iterative version of the DFS solution presented above?

Answer 1

Does this pseudocode help? Let me know of any clarifications.

stack_0.push(0) // stack containing only vertex 0
stack_of_stacks = empty
stack_of_stacks.push((stack_0, vertex 0)) // added a tuple of stack and vertex 0
while stack_of_stacks is not empty:
  (temp_stack, temp_vertex) = stack_of_stacks.pop()

  if temp_vertex = n-1
        print temp_stack
  else, for every y in graph[temp_vertex]
        new_stack = temp_stack
        new_stack.push(y)
        new_vertex = y
        stack_of_stacks.push((new_stack, new_vertex))

end