diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 0000000..4ba005a
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,110 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/python
+{
+	"name": "Python 3",
+	// Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
+	"image": "mcr.microsoft.com/devcontainers/python:1-3.10-bullseye",
+	// Features to add to the dev container. More info: https://containers.dev/features.
+	// "features": {},
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	"forwardPorts": [
+		8080
+	],
+	// Use 'postCreateCommand' to run commands after the container is created.
+	"postCreateCommand": "pip3 install --user -r requirements.txt",
+	// Configure tool-specific properties.
+	"customizations": {
+		// Configure properties specific to VS Code.
+		"vscode": {
+			// Set *default* container specific settings.json values on container create.
+			"settings": {
+				"editor.formatOnSave": true,
+				"files.autoSave": "afterDelay",
+				"editor.formatOnPaste": true,
+				"editor.fontSize": 15,
+				"workbench.iconTheme": "material-icon-theme",
+				// to do tree settings
+				"todo-tree.highlights.defaultHighlight": {
+					"icon": "alert",
+					"type": "text-and-comment",
+					"foreground": "#ffffff",
+					// "background": "#808080",
+					"opacity": 70,
+					"iconColour": "#0000FF",
+					"gutterIcon": true
+				},
+				"todo-tree.highlights.customHighlight": {
+					"TODO": {
+						"icon": "tools",
+						// "foreground": "#000000",
+						// "background": "#FFFFFF",
+						"iconColour": "#FFFFFF"
+					},
+					"NOTE": {
+						"icon": "note",
+						"foreground": "#e404f8",
+						// "background": "#808080",
+						"iconColour": "#e404f8"
+					},
+					"QUESTION": {
+						"icon": "question",
+						"foreground": "#FFFF00",
+						// "background": "#FFFF00",
+						"iconColour": "#FFFF00"
+					},
+					"FIXME": {
+						"foreground": "#000000",
+						"background": "#FFFF00",
+						"iconColour": "#FFFF00"
+					},
+					"BUG": {
+						"foreground": "#000000",
+						"background": "#FF0000",
+						"iconColour": "#FF0000"
+					},
+					"DEBUG": {
+						"foreground": "#FFFF00",
+						// "background": "#FF0000",
+						"iconColour": "#FFFF00"
+					},
+					"SOLVED": {
+						"icon": "check",
+						"foreground": "#FFFFFF",
+						"background": "#00FF00",
+						"iconColour": "#00FF00"
+					}
+				},
+				"todo-tree.general.tags": [
+					"TODO",
+					"NOTE",
+					"QUESTION",
+					"FIXME",
+					"BUG",
+					"DEBUG",
+					"SOLVED"
+				],
+				"todo-tree.regex.regex": "(//|#|<!--|;|/\\*|^|^\\s*(-|\\d+.))\\s*($TAGS).*(\\n\\s*//\\s{2,}.*)*",
+				"todo-tree.tree.autoRefresh": true,
+				"indentRainbow.ignoreErrorLanguages": [
+					"markdown",
+					"python",
+					"cpp"
+				]
+			},
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"ms-python.python",
+				"ms-python.debugpy",
+				"ms-toolsai.jupyter",
+				"ms-python.autopep8",
+				"ms-python.flake8",
+				"oderwat.indent-rainbow",
+				"gruntfuggly.todo-tree",
+				"pkief.material-icon-theme"
+			]
+		}
+		
+	}
+	// Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
+	// "remoteUser": "root"
+}
\ No newline at end of file
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..f33a02c
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,12 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for more information:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+# https://containers.dev/guide/dependabot
+
+version: 2
+updates:
+ - package-ecosystem: "devcontainers"
+   directory: "/"
+   schedule:
+     interval: weekly
diff --git a/data_structures/4_HashTable_2_Collisions/4_hash_table_collision_handling.ipynb b/data_structures/4_HashTable_2_Collisions/4_hash_table_collision_handling.ipynb
index 0cebc4e..947ced9 100644
--- a/data_structures/4_HashTable_2_Collisions/4_hash_table_collision_handling.ipynb
+++ b/data_structures/4_HashTable_2_Collisions/4_hash_table_collision_handling.ipynb
@@ -110,51 +110,79 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 86,
+   "execution_count": 70,
    "metadata": {},
    "outputs": [],
    "source": [
-    "class HashTable:  \n",
-    "    def __init__(self):\n",
-    "        self.MAX = 10\n",
-    "        self.arr = [[] for i in range(self.MAX)]\n",
-    "        \n",
+    "class HashTable(object):\n",
+    "    def __init__(self, max_item:int=10) -> None:\n",
+    "        super().__init__()\n",
+    "        self.max_item = max_item\n",
+    "        self.arr = [[] for _ in range(self.max_item)]\n",
+    "    \n",
     "    def get_hash(self, key):\n",
     "        hash = 0\n",
     "        for char in key:\n",
     "            hash += ord(char)\n",
-    "        return hash % self.MAX\n",
+    "        return hash % self.max_item\n",
+    "\n",
+    "    def __setitem__(self, key, val):\n",
+    "        hash_value = self.get_hash(key)\n",
+    "        if self.arr[hash_value] == []:\n",
+    "            self.arr[hash_value].append([key,val])\n",
+    "            print(f\"added new entry for {key}\")\n",
+    "        else:\n",
+    "            found = False\n",
+    "            for item in self.arr[hash_value]:\n",
+    "                if item[0] == key:\n",
+    "                    print(f\"replacing value for key {key}\")\n",
+    "                    item[1] = val\n",
+    "                    found = True\n",
+    "            if not found:\n",
+    "                self.arr[hash_value].append([key,val])\n",
+    "                print(f\"appended new entry for {key}\")\n",
     "    \n",
     "    def __getitem__(self, key):\n",
-    "        arr_index = self.get_hash(key)\n",
-    "        for kv in self.arr[arr_index]:\n",
-    "            if kv[0] == key:\n",
-    "                return kv[1]\n",
-    "            \n",
-    "    def __setitem__(self, key, val):\n",
-    "        h = self.get_hash(key)\n",
-    "        found = False\n",
-    "        for idx, element in enumerate(self.arr[h]):\n",
-    "            if len(element)==2 and element[0] == key:\n",
-    "                self.arr[h][idx] = (key,val)\n",
-    "                found = True\n",
-    "        if not found:\n",
-    "            self.arr[h].append((key,val))\n",
-    "        \n",
+    "        hash_value = self.get_hash(key)\n",
+    "        if len(self.arr[hash_value]) == 1:\n",
+    "            return self.arr[hash_value][0][1]\n",
+    "        else:\n",
+    "            for item in self.arr[hash_value]:\n",
+    "                if item[0] == key:\n",
+    "                    return item[1]\n",
+    "                \n",
     "    def __delitem__(self, key):\n",
-    "        arr_index = self.get_hash(key)\n",
-    "        for index, kv in enumerate(self.arr[arr_index]):\n",
-    "            if kv[0] == key:\n",
-    "                print(\"del\",index)\n",
-    "                del self.arr[arr_index][index]\n",
-    "        "
+    "        print(\"inside delete function\")\n",
+    "        hash_value = self.get_hash(key)\n",
+    "        print(hash_value)\n",
+    "        if len(self.arr[hash_value]) == 1:\n",
+    "            f\"replacing the value for key {key} with empty list\"\n",
+    "            self.arr[hash_value] = []\n",
+    "        else:\n",
+    "            for item in self.arr[hash_value]:\n",
+    "                print(f\"item: {item}, key: {key}\")\n",
+    "                if item[0] == key:\n",
+    "                    f\"setting the value for key {key} with empty list\"\n",
+    "                    item = []\n",
+    "                    "
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 87,
+   "execution_count": 71,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "added new entry for march 6\n",
+      "added new entry for march 7\n",
+      "added new entry for march 8\n",
+      "appended new entry for march 17\n"
+     ]
+    }
+   ],
    "source": [
     "t = HashTable()\n",
     "t[\"march 6\"] = 310\n",
@@ -165,7 +193,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 88,
+   "execution_count": 72,
    "metadata": {
     "scrolled": true
    },
@@ -176,7 +204,7 @@
        "310"
       ]
      },
-     "execution_count": 88,
+     "execution_count": 72,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -187,7 +215,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 89,
+   "execution_count": 73,
    "metadata": {
     "scrolled": true
    },
@@ -198,7 +226,7 @@
        "63457"
       ]
      },
-     "execution_count": 89,
+     "execution_count": 73,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -209,14 +237,14 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 90,
+   "execution_count": 74,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "[[('march 7', 420)],\n",
-       " [('march 8', 67)],\n",
+       "[[['march 7', 420]],\n",
+       " [['march 8', 67]],\n",
        " [],\n",
        " [],\n",
        " [],\n",
@@ -224,10 +252,10 @@
        " [],\n",
        " [],\n",
        " [],\n",
-       " [('march 6', 310), ('march 17', 63457)]]"
+       " [['march 6', 310], ['march 17', 63457]]]"
       ]
      },
-     "execution_count": 90,
+     "execution_count": 74,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -238,25 +266,33 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 91,
+   "execution_count": 75,
    "metadata": {
     "scrolled": true
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "replacing value for key march 6\n"
+     ]
+    }
+   ],
    "source": [
     "t[\"march 6\"] = 11"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 92,
+   "execution_count": 76,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "[[('march 7', 420)],\n",
-       " [('march 8', 67)],\n",
+       "[[['march 7', 420]],\n",
+       " [['march 8', 67]],\n",
        " [],\n",
        " [],\n",
        " [],\n",
@@ -264,10 +300,10 @@
        " [],\n",
        " [],\n",
        " [],\n",
-       " [('march 6', 11), ('march 17', 63457)]]"
+       " [['march 6', 11], ['march 17', 63457]]]"
       ]
      },
-     "execution_count": 92,
+     "execution_count": 76,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -278,16 +314,16 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 68,
+   "execution_count": 77,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "310"
+       "11"
       ]
      },
-     "execution_count": 68,
+     "execution_count": 77,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -298,20 +334,50 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 48,
+   "execution_count": 78,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "del 0\n"
+      "inside delete function\n",
+      "9\n",
+      "item: ['march 6', 11], key: march 6\n",
+      "item: ['march 17', 63457], key: march 6\n"
      ]
     }
    ],
    "source": [
     "del t[\"march 6\"]"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 79,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "11"
+      ]
+     },
+     "execution_count": 79,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "t[\"march 6\"]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {
@@ -330,7 +396,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.3"
+   "version": "3.10.14"
   }
  },
  "nbformat": 4,
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..2d3a47f
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,3 @@
+rope
+flake8
+jupyterlab
\ No newline at end of file