Separating functions in Question1

Author: mandana-g

02_activities/assignments/assignment_1.ipynb

@@ -88,7 +88,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
+   "execution_count": null,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -123,36 +123,39 @@
     "    \n",
     "    return root\n",
     "\n",
-    "# Finding the duplicate\n",
-    "def find_duplicate(root):\n",
-    "    visited = set()\n",
-    "    closest_duplicate = None \n",
-    "    min_depth = float('inf') # Setting minimum depth infinite as any valid depth in the tree will be smaller than infinity\n",
+    "def dfs(node, depth, visited):\n",
+    "    if node is None:\n",
+    "        return None, float('inf')  # No duplicate, infinite depth\n",
     "\n",
-    "    def dfs(node, depth):\n",
-    "        nonlocal closest_duplicate, min_depth\n",
-    "        \n",
-    "        if node is None:\n",
-    "            return\n",
-    "        \n",
-    "        if node.val in visited:\n",
-    "            if depth < min_depth: \n",
-    "                closest_duplicate = node.val\n",
-    "                min_depth = depth\n",
-    "        else:\n",
-    "            visited.add(node.val)\n",
+    "    # If the node's value has already been visited, it's a duplicate\n",
+    "    if node.val in visited:\n",
+    "        return node.val, depth  # Found a duplicate at this depth\n",
+    "    \n",
+    "    visited.add(node.val)\n",
+    "\n",
+    "    # Recurse on left and right children and return the closest duplicate\n",
+    "    left_val, left_depth = dfs(node.left, depth + 1, visited)\n",
+    "    right_val, right_depth = dfs(node.right, depth + 1, visited)\n",
+    "\n",
+    "    # Compare which duplicate is closer to the root\n",
+    "    if left_depth < right_depth:\n",
+    "        return left_val, left_depth\n",
+    "    else:\n",
+    "        return right_val, right_depth\n",
     "\n",
-    "        dfs(node.left, depth + 1)\n",
-    "        dfs(node.right, depth + 1)\n",
     "\n",
-    "    dfs(root, 0)\n",
+    "def find_duplicate(root):\n",
+    "    visited = set()  # To track visited node values\n",
+    "    closest_duplicate, min_depth = dfs(root, 0, visited)\n",
     "    \n",
-    "    return closest_duplicate if closest_duplicate is not None else -1\n"
+    "    # Return the closest duplicate if found, otherwise return -1\n",
+    "    return closest_duplicate if closest_duplicate is not None else -1\n",
+    "\n"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 21,
    "metadata": {},
    "outputs": [
     {
@@ -172,34 +175,14 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
-   "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "Duplicate value: -1\n"
-     ]
-    }
-   ],
-   "source": [
-    "example_roots = [10, 9, 8, 7]   # Testing the example 2\n",
-    "root = build_tree(example_roots)\n",
-    "duplicate = find_duplicate(root)\n",
-    "print(f\"Duplicate value: {duplicate}\") "
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 22,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Duplicate value: 10\n"
+      "Duplicate value: 12\n"
      ]
     }
    ],
@@ -212,7 +195,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 17,
    "metadata": {},
    "outputs": [
     {