public static void main(String[] args) {
BinaryTreeNode A1 = new BinaryTreeNode(8);
BinaryTreeNode A2 = new BinaryTreeNode(8);
BinaryTreeNode A3 = new BinaryTreeNode(7);
BinaryTreeNode A4 = new BinaryTreeNode(9);
BinaryTreeNode A5 = new BinaryTreeNode(2);
BinaryTreeNode A6 = new BinaryTreeNode(4);
BinaryTreeNode A7 = new BinaryTreeNode(7);
A1.leftNode = A2;
A1.rightNode = A3;
A2.leftNode = A4;
A2.rightNode = A5;
A5.leftNode = A6;
A5.rightNode = A7;
mirror(A1);
System.out.println(A1.leftNode + " " + A1.rightNode);
System.out.println(A1.rightNode.leftNode + " " + A1.rightNode.rightNode);
}
public static void mirror(BinaryTreeNode root) {
Stack<BinaryTreeNode> stack = new Stack<>();
if (root == null) return;
stack.push(root);
while (!stack.isEmpty()) {
BinaryTreeNode curr = stack.pop();
if (curr.leftNode != null || curr.rightNode != null) {
BinaryTreeNode temp = curr.leftNode;
curr.leftNode = curr.rightNode;
curr.rightNode = temp;
}
if (curr.rightNode != null) stack.push(curr.rightNode);
if (curr.leftNode != null) stack.push(curr.leftNode);
}
}