二分搜索树python。迭代搜索

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

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

    def insert(self, val):
        if not self.root:
            self.root = TreeNode(val)
        else:
            self._insert(self.root, val)

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

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

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

    def delete(self, val):
        self.root = self._delete(self.root, val)

    def _delete(self, node, val):
        if not node:
            return None
        if val < node.val:
            node.left = self._delete(node.left, val)
        elif val > node.val:
            node.right = self._delete(node.right, val)
        else:
            if not node.left:
                return node.right
            elif not node.right:
                return node.left
            else:
                min_node = self._find_min(node.right)
                node.val = min_node.val
                node.right = self._delete(node.right, min_node.val)
        return node

    def _find_min(self, node):
        while node.left:
            node = node.left
        return node

def iterative_search(root, val):
    while root:
        if root.val == val:
            return root
        elif val < root.val:
            root = root.left
        else:
            root = root.right
    return None