046Invert Binary Tree

def invertTree(root):
    if not root:
        return None
    # Swap children
    root.left, root.right = root.right, root.left
    # Recurse on both subtrees
    invertTree(root.left)
    invertTree(root.right)
    return root

public TreeNode invertTree(TreeNode root) {
    if (root == null) return null;
    // Swap children
    TreeNode temp = root.left;
    root.left = root.right;
    root.right = temp;
    // Recurse
    invertTree(root.left);
    invertTree(root.right);
    return root;
}

fun invertTree(root: TreeNode?): TreeNode? {
    if (root == null) return null
    // Swap children
    val temp = root.left
    root.left = root.right
    root.right = temp
    // Recurse
    invertTree(root.left)
    invertTree(root.right)
    return root
}

TreeNode* invertTree(TreeNode* root) {
    if (!root) return nullptr;
    swap(root->left, root->right);
    invertTree(root->left);
    invertTree(root->right);
    return root;
}