Interview Question for Software Engineer at Google:

// Traverse the tree and count the depth at every leaf. The maximum count is
// the depth of the tree

// SInce recursion is not allowed use a Stack. Any recursive problem can be solved
// iteratively by using a stack

// Rough skeleton code, without testing
class TraverseTree {
  public:
     Traverse_Tree { curr_depth = max_depth = 0; }

     void push(Node& n);
     int get_depth() { return max_depth }
     void inc_depth()'; { curr_depth++; }
     void set_max_depth { if (curr_depth > max_depth) max_depth = curr_depth; }

  private:
     int curr_depth;
     int max_depth;

  }

int bst_depth (const Node& root)
{
   Traverse_Tree t;
   const Node& n = root;

    while (n) {
         t.inc_depth();
         t.push(n);
         if (n->left) {
             n = n->left
             continue
         } else if (n->right) {
          // same as for left tree
          .....
        } else [
          // leaf node
           t.set_max_depth();
           n = t.pop()->right ;
           t_dec_depth();
      }

   }

   return t.get_depth();