Trees आणि Binary Search Tree

class TreeNode:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

class BST:
    def __init__(self):
        self.root = None

    def insert(self, val):
        self.root = self._insert(self.root, val)

    def _insert(self, node, val):
        if not node:
            return TreeNode(val)
        if val < node.val:
            node.left = self._insert(node.left, val)
        elif val > node.val:
            node.right = self._insert(node.right, val)
        return node

    def search(self, val):
        return self._search(self.root, val)

    def _search(self, node, val):
        if not node:
            return False
        if val == node.val:
            return True
        elif val < node.val:
            return self._search(node.left, val)
        else:
            return self._search(node.right, val)

def inorder(node):    # Left → Root → Right (sorted order!)
    if node:
        inorder(node.left)
        print(node.val, end=" ")
        inorder(node.right)

def preorder(node):   # Root → Left → Right
    if node:
        print(node.val, end=" ")
        preorder(node.left)
        preorder(node.right)

def postorder(node):  # Left → Right → Root
    if node:
        postorder(node.left)
        postorder(node.right)
        print(node.val, end=" ")

# BST: 5 inserted, then 3, 7, 1, 4
# Inorder: 1 3 4 5 7 (sorted!)