Binary Search Tree

binary_search_tree.py

@@ -0,0 +1,87 @@
+class TreeNode:
+    def __init__(self, key):
+        self.key = key
+        self.left = None
+        self.right = None
+
+    def __str__(self):
+        return str(self.key)
+
+
+class BinarySearchTree:
+    def __init__(self):
+        self.root = None
+
+    def insert(self,key):
+        self.root = self._insert(self.root, key)
+
+    def _insert(self, node, key):
+        if node is None:
+            return TreeNode(key)
+        if key < node.key:
+            node.left = self._insert(node.left, key)
+        elif key > node.key:
+            node.right = self._insert(node.right, key)
+        return node
+
+    def search(self, key):
+        return self._search(self.root, key)
+
+    def _search(self, node, key):
+        if node is None or node.key == key:
+            return node
+        if key < node.key:
+            return self._search(node.left, key)
+        return self._search(node.right, key)
+
+    def delete(self, key):
+        self.root = self._delete(self.root, key)
+
+    def _delete(self, node, key):
+        if node is None:
+            return node
+        if key < node.key:
+            node.left = self._delete(node.left, key)
+        elif key > node.key:
+            node.right = self._delete(node.right, key)
+        else:
+            if node.left is None:
+                return node.right
+
+            elif node.right is None:
+                return node.left
+
+            node.key = self._min_value(node.right)
+            node.right = self._delete(node.right, node.key)
+        return node
+
+    def _min_value(self, node):
+        while node.left is not None:
+            node = node.left
+        return node.key
+
+    def inorder_traversal(self):
+        result = []
+        self._inorder_traversal(self.root, result)
+        return result
+
+    def _inorder_traversal(self, node, result):
+        if node:
+            self._inorder_traversal(node.left, result)
+            result.append(node.key)
+            self._inorder_traversal(node.right, result)
+
+
+bst = BinarySearchTree()
+nodes = [50, 30, 20, 40, 70, 60, 80]
+
+for node in nodes:
+    bst.insert(node)
+
+
+print("Inorder traversal:", bst.inorder_traversal())
+print("Search for 40:", bst.search(40))
+
+bst.delete(20)
+
+print("Inorder traversal after deleting 40:", bst.inorder_traversal())