diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..f735b2df
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,34 @@
+name: Run Tests
+
+on:
+  [ push, pull_request ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.8'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+
+      - name: Install mypy
+        run: |
+          python -m pip install mypy
+
+      - name: Run mypy
+        run: |
+          mypy .
+
+      - name: Run tests
+        run: |
+          python ./scripts/run_tests.py
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 00000000..624cd195
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,2 @@
+[mypy]
+exclude = venv/
diff --git a/project/treap.py b/project/treap.py
new file mode 100644
index 00000000..35264f00
--- /dev/null
+++ b/project/treap.py
@@ -0,0 +1,280 @@
+from collections.abc import MutableMapping
+from typing import Optional
+
+
+class TreapNode:
+    """A node in the Treap data structure.
+
+    A TreapNode represents a single node in the Treap, which combines properties
+    of a binary search tree (BST) and a heap. Each node stores a key, a value, and
+    references to its left and right children.
+
+    Attributes:
+        key: The key of the node, used for BST ordering.
+        value: The value associated with the key, used for heap ordering.
+        left (Optional[TreapNode]): The left child of the node, or None.
+        right (Optional[TreapNode]): The right child of the node, or None.
+    """
+
+    key = None
+    value = None
+    left = None
+    right = None
+
+    def __init__(self, key, value):
+        """Initialize a new TreapNode with a key and value.
+
+        Args:
+            key: The key of the node, used for BST ordering.
+            value: The value of the node, used for heap ordering.
+        """
+        self.key = key
+        self.value = value
+        self.left = None
+        self.right = None
+
+
+class Treap(MutableMapping):
+    """A Treap data structure that combines a binary search tree and a heap.
+
+    The Treap (Tree + Heap) is a randomized self-balancing binary search tree where
+    each node has a key and a value. The keys maintain BST properties (left subtree
+    keys are less than the node's key, right subtree keys are greater), and the values
+    maintain heap properties (a parent's value is greater than its children's values).
+    This implementation inherits from MutableMapping, providing dictionary-like
+    functionality.
+
+    Attributes:
+        root (Optional[TreapNode]): The root node of the Treap, or None if the Treap
+            is empty.
+    """
+
+    def __init__(self):
+        """Initialize an empty Treap."""
+        self.root = None
+
+    def __getitem__(self, key):
+        """Retrieve the value associated with the given key.
+
+        Args:
+            key: The key to look up in the Treap.
+
+        Returns:
+            The value associated with the key.
+
+        Raises:
+            KeyError: If the key is not found in the Treap.
+        """
+        node = self.find(self.root, key)
+        if node is not None:
+            return node.value
+        raise KeyError(f"Key {key} not found in Treap")
+
+    def __setitem__(self, key, value):
+        """Insert or update a key-value pair in the Treap.
+
+        Args:
+            key: The key to insert or update.
+            value: The value to associate with the key.
+        """
+        self.insert_node(key, value)
+
+    def __delitem__(self, key):
+        """Remove a key-value pair from the Treap.
+
+        Args:
+            key: The key to remove.
+
+        Raises:
+            KeyError: If the key is not found in the Treap.
+        """
+        self.root = self.remove(self.root, key)
+
+    def __iter__(self):
+        """Return an iterator over the keys in the Treap.
+
+        The keys are returned in sorted order (inorder traversal).
+
+        Returns:
+            An iterator yielding the keys in the Treap.
+        """
+        return self.inorder(self.root)
+
+    def __len__(self):
+        """Return the number of nodes in the Treap.
+
+        Returns:
+            int: The number of key-value pairs in the Treap.
+        """
+        return self.count_nodes(self.root)
+
+    def inorder(self, node):
+        """Perform an inorder traversal of the Treap starting from the given node.
+
+        Args:
+            node: The root node of the subtree to traverse, or None.
+
+        Yields:
+            The keys of the nodes in inorder (sorted) order.
+        """
+        if node is not None:
+            yield from self.inorder(node.left)
+            yield node.key
+            yield from self.inorder(node.right)
+
+    def count_nodes(self, node):
+        """Count the number of nodes in the subtree rooted at the given node.
+
+        Args:
+            node: The root node of the subtree to count, or None.
+
+        Returns:
+            int: The number of nodes in the subtree.
+        """
+        if node is None:
+            return 0
+        return 1 + self.count_nodes(node.left) + self.count_nodes(node.right)
+
+    def preorder(self, node: Optional[TreapNode]):
+        """Perform a preorder traversal of the Treap starting from the given node.
+
+        Args:
+            node: The root node of the subtree to traverse, or None.
+
+        Yields:
+            The keys of the nodes in preorder (root, left, right) order.
+        """
+        if node is not None:
+            yield node.key
+            yield from self.preorder(node.left)
+            yield from self.preorder(node.right)
+
+    def postorder(self, node: Optional[TreapNode]):
+        """Perform a postorder traversal of the Treap starting from the given node.
+
+        Args:
+            node: The root node of the subtree to traverse, or None.
+
+        Yields:
+            The keys of the nodes in postorder (left, right, root) order.
+        """
+        if node is not None:
+            yield from self.postorder(node.left)
+            yield from self.postorder(node.right)
+            yield node.key
+
+    def insert_node(self, key, value):
+        """Insert a new key-value pair into the Treap.
+
+        Args:
+            key: The key to insert.
+            value: The value to associate with the key.
+        """
+        new_node = TreapNode(key, value)
+        if self.root is None:
+            self.root = new_node
+            return
+        else:
+            left, right = self.split(self.root, key)
+            self.root = self.merge(left, new_node)
+            self.root = self.merge(self.root, right)
+
+    def remove(self, root: Optional[TreapNode], key):
+        """Remove a node with the given key from the subtree.
+
+        Args:
+            root: The root node of the subtree to remove from, or None.
+            key: The key to remove.
+
+        Returns:
+            Optional[TreapNode]: The new root of the subtree after removal, or None
+                if the subtree is empty.
+
+        Raises:
+            KeyError: If the key is not found in the Treap.
+        """
+        if root is None:
+            return None
+        elif root.key < key:
+            root.right = self.remove(root.right, key)
+        elif root.key > key:
+            root.left = self.remove(root.left, key)
+        else:
+            root = self.merge(root.left, root.right)
+        return root
+
+    def split(self, root: Optional[TreapNode], key):
+        """Split the Treap into two subtrees based on the given key.
+
+        Args:
+            root: The root node of the subtree to split, or None.
+            key: The key to split on.
+
+        Returns:
+            Tuple[Optional[TreapNode], Optional[TreapNode]]: A tuple of two subtrees:
+                - The left subtree contains all nodes with keys less than the given key.
+                - The right subtree contains all nodes with keys greater than or equal
+                  to the given key.
+        """
+        if root is None:
+            return None, None
+        elif root.key < key:
+            (left, right) = self.split(root.right, key)
+            root.right = left
+            return root, right
+        else:
+            (left, right) = self.split(root.left, key)
+            root.left = right
+            return left, root
+
+    def merge(self, left: Optional[TreapNode], right: Optional[TreapNode]):
+        """Merge two Treaps into one while maintaining BST and heap properties.
+
+        Args:
+            left: The root of the left Treap, or None.
+            right: The root of the right Treap, or None.
+
+        Returns:
+            Optional[TreapNode]: The root of the merged Treap, or None if both inputs
+                are None.
+
+        Notes:
+            Assumes that all keys in the left Treap are less than all keys in the right
+            Treap. The heap property is maintained by comparing the values of the nodes.
+        """
+        if left is None:
+            return right
+        elif right is None:
+            return left
+        else:
+            if (left.value is None) | (right.value is None):
+                return None
+
+            assert left.value is not None
+            assert right.value is not None
+
+            if left.value > right.value:
+                left.right = self.merge(left.right, right)
+                return left
+            else:
+                right.left = self.merge(right.left, left)
+                return right
+
+    def find(self, root: Optional[TreapNode], key):
+        """Find a node with the given key in the subtree.
+
+        Args:
+            root: The root node of the subtree to search in, or None.
+            key: The key to search for.
+
+        Returns:
+            Optional[TreapNode]: The node with the given key, or None if the key is not
+                found.
+        """
+        if root is None:
+            return None
+        elif root.key < key:
+            return self.find(root.right, key)
+        elif root.key > key:
+            return self.find(root.left, key)
+        return root
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..eba99035
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,21 @@
+import pytest
+
+from project.treap import Treap, TreapNode
+
+
+@pytest.fixture
+def empty_tree():
+    return Treap()
+
+
+@pytest.fixture
+def filled_tree():
+    tree = Treap()
+    # Добавляем узлы, чтобы значения value у родителя всегда были больше значений детей
+    tree.insert_node(10, 100)
+    tree.insert_node(5, 80)
+    tree.insert_node(15, 60)
+    tree.insert_node(7, 90)
+    tree.insert_node(12, 70)
+    tree.insert_node(18, 50)
+    return tree
diff --git a/tests/test_basic.py b/tests/test_basic.py
deleted file mode 100644
index 4811167b..00000000
--- a/tests/test_basic.py
+++ /dev/null
@@ -1,18 +0,0 @@
-import pytest
-import project  # on import will print something from __init__ file
-
-
-def setup_module(module):
-    print("basic setup module")
-
-
-def teardown_module(module):
-    print("basic teardown module")
-
-
-def test_1():
-    assert 1 + 1 == 2
-
-
-def test_2():
-    assert "1" + "1" == "11"
diff --git a/tests/test_treap_contains_len.py b/tests/test_treap_contains_len.py
new file mode 100644
index 00000000..92778d68
--- /dev/null
+++ b/tests/test_treap_contains_len.py
@@ -0,0 +1,19 @@
+import pytest
+
+
+def test_contains_operator(filled_tree, empty_tree):
+    assert 10 not in empty_tree, "Empty tree should not contain any key"
+
+    assert 10 in filled_tree, "Key 10 should be in the filled tree"
+    assert 5 in filled_tree, "Key 5 should be in the filled tree"
+    assert 15 in filled_tree, "Key 15 should be in the filled tree"
+    assert 7 in filled_tree, "Key 7 should be in the filled tree"
+    assert 12 in filled_tree, "Key 12 should be in the filled tree"
+    assert 18 in filled_tree, "Key 18 should be in the filled tree"
+    assert 100 not in filled_tree, "Key 100 should not be in the filled tree"
+
+
+def test_len_function(filled_tree, empty_tree):
+    # Проверка количества узлов в дереве
+    assert len(filled_tree) == 6, "Tree should have 6 nodes"
+    assert len(empty_tree) == 0, "Empty tree should have 0 nodes"
diff --git a/tests/test_treap_delete.py b/tests/test_treap_delete.py
new file mode 100644
index 00000000..290e097c
--- /dev/null
+++ b/tests/test_treap_delete.py
@@ -0,0 +1,9 @@
+import pytest
+
+
+def test_delete_item(filled_tree):
+    # Проверка удаления узла
+    filled_tree.__delitem__(5)
+    with pytest.raises(KeyError):
+        _ = filled_tree[5]
+    assert filled_tree[10] == 100, "Root node with key 10 should still exist"
diff --git a/tests/test_treap_insert_get.py b/tests/test_treap_insert_get.py
new file mode 100644
index 00000000..33af29c7
--- /dev/null
+++ b/tests/test_treap_insert_get.py
@@ -0,0 +1,14 @@
+import pytest
+
+
+def test_insert_and_get_item(empty_tree):
+    # Проверка вставки и получения значения
+    empty_tree[10] = 100
+    empty_tree[5] = 80
+    assert empty_tree[10] == 100, "Value for key 10 should be 100"
+    assert empty_tree[5] == 80, "Value for key 5 should be 80"
+
+
+def test_get_nonexistent_key(empty_tree):
+    with pytest.raises(KeyError):
+        _ = empty_tree[100]
diff --git a/tests/test_treap_properties.py b/tests/test_treap_properties.py
new file mode 100644
index 00000000..5cdb3469
--- /dev/null
+++ b/tests/test_treap_properties.py
@@ -0,0 +1,17 @@
+import pytest
+
+
+def test_heap_property(filled_tree):
+    # Проверка свойства кучи (value родителя > value детей) для Treap
+    def check_heap_property(node):
+        if node is None:
+            return True
+        if node.left and node.left.value > node.value:
+            return False
+        if node.right and node.right.value > node.value:
+            return False
+        return check_heap_property(node.left) and check_heap_property(node.right)
+
+    assert check_heap_property(
+        filled_tree.root
+    ), "Heap property (parent value > children values) should hold for all nodes"
diff --git a/tests/test_treap_traversal.py b/tests/test_treap_traversal.py
new file mode 100644
index 00000000..0038b735
--- /dev/null
+++ b/tests/test_treap_traversal.py
@@ -0,0 +1,24 @@
+import pytest
+
+
+def test_inorder_key_bst(filled_tree):
+    expected_list = [5, 7, 10, 12, 15, 18]
+    assert expected_list == list(filled_tree.inorder(filled_tree.root))
+
+
+def test_inorder_traversal(filled_tree):
+    # Проверка обхода inorder
+    expected_inorder = [5, 7, 10, 12, 15, 18]
+    assert (
+        list(filled_tree.inorder(filled_tree.root)) == expected_inorder
+    ), "Inorder traversal does not match expected output"
+
+
+def test_preorder_traversal(filled_tree):
+    expected_preorder = [10, 7, 5, 12, 15, 18]
+    assert list(filled_tree.preorder(filled_tree.root)) == expected_preorder
+
+
+def test_postorder_traversal(filled_tree):
+    expected_postorder = [5, 7, 18, 15, 12, 10]
+    assert list(filled_tree.postorder(filled_tree.root)) == expected_postorder