    },
    "language_info": {
     "codemirror_mode": {
      "name": "ipython",
      "version": 2
     },
     "file_extension": ".py",
     "mimetype": "text/x-python",
     "name": "python",
     "nbconvert_exporter": "python",
 
</s> remove    "pygments_lexer": "ipython2",
   "version": "2.7.10"
 </s> add    "pygments_lexer": "ipython3",
   "version": "3.4.3" </s> remove    "name": "python2"
 </s> add    "name": "python3" </s> remove    "display_name": "Python 2",
 </s> add    "display_name": "Python 3", </s> remove     "* Space: O(h), where h is the height of the tree\n",
 </s> add     "* Space: O(m), where m is the recursion depth, or O(1) if using an iterative approach\n", </s> remove     "* Space: O(h), where h is the height of the tree\n",
 </s> add     "* Space: O(m), where m is the recursion depth, or O(1) if using an iterative approach\n",
    "version": 3
    },
    "language_info": {
     "codemirror_mode": {
      "name": "ipython",
    "version": 3
     },
     "file_extension": ".py",
     "mimetype": "text/x-python",
     "name": "python",
     "nbconvert_exporter": "python",
keep keep keep keep replace keep keep keep keep keep
 Update dfs solution complexity discussion 
graphs_trees/tree_dfs/dfs_solution.ipynb