BT

//BFS
    public String toStringBreadthFirst() {
        StringBuilder result = new StringBuilder();
        if (root != null) {
            Queue<Node<T>> nodes = new LinkedList<>();
            nodes.add(root);
            while (!nodes.isEmpty()) {
                Node<T> current = nodes.remove();
                result.append("Key:").append(current.key).append("; Value:").append(current.value).append("\n");
                if (current.left != null) {
                    nodes.add(current.left);
                }

                if (current.right != null) {
                    nodes.add(current.right);
                }
            }
        } else {
            result.append("");
        }
        return result.toString();
    }

// DFS
    public String toString() {
        StringBuilder result = new StringBuilder();
        return recursiveDepthFirst(root, result);
    }

    private String recursiveDepthFirst(Node<T> current, StringBuilder result) {
        if (current != null) {
            recursiveDepthFirst(current.left, result);
            result.append("Key:").append(current.key).append("; Value:").append(current.value).append("\n");
            recursiveDepthFirst(current.right, result);
        }
        return result.toString();
    }

//УДАЛЕНИЕ
    public void delete(int key) {
        root = deleteRecursively(root, key);
    }

    private Node<T> deleteRecursively(Node<T> current, int key) {
        if (current == null) {
            return null;
        }
        if (key < current.key) {
            current.left = deleteRecursively(current.left, key);
            return current;
        } else if (key > current.key) {
            current.right = deleteRecursively(current.right, key);
            return current;
        }
        if (current.left == null) {
            return current.right;
        } else if (current.right == null) {
            return current.left;
        } else {
            current.key = findSmallestKey(current.right);
            current.right = deleteRecursively(current.right, current.key);
            return current;
        }
    }

    private int findSmallestKey(Node<T> current) {
        return current.left == null ? current.key : findSmallestKey(current.left);
    }