     "metadata": {},
     "source": [
      "## Test Cases\n",
      "\n",
      "### Breadth-First Search\n",
      "* 5, 2, 8, 1, 3 -> 5, 2, 8, 1, 3"
     ]
    },
    {
     "cell_type": "markdown",
 
</s> remove     "### Breadth-First Search\n",
 </s> add     "### Breadth-First Traversal\n", </s> remove     "## Problem: Implement breadth-first search on a binary tree.\n",
 </s> add     "## Problem: Implement breadth-first traversal on a binary tree.\n", </s> remove     "## Problem: Implement breadth-first search on a binary tree.\n",
 </s> add     "## Problem: Implement breadth-first traversal on a binary tree.\n", </s> remove     "* Space: O(n)"
 </s> add     "* Space: O(n), extra space for the queue" </s> remove     "    * Yes"
 </s> add     "    * Yes\n",
    "* Can we assume this fits in memory?\n",
    "    * Yes\n",
    "* What should we do with each node when we process it?\n",
    "    * Call an input method `visit_func` on the node"
    "### Breadth-First Traversal\n",
     "metadata": {},
     "source": [
      "## Test Cases\n",
      "\n",
    "### Breadth-First Traversal\n",
      "* 5, 2, 8, 1, 3 -> 5, 2, 8, 1, 3"
     ]
    },
    {
     "cell_type": "markdown",
keep keep keep keep replace keep keep keep keep keep
 Polish tree bfs challenge and solution (#77)

Update constraints and algorithm discussion. 
graphs_trees/tree_bfs/bfs_challenge.ipynb