// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/invert-a-binary-tree

var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
function Node(value) {
  this.value = value;
  this.left = null;
  this.right = null;
}
function BinarySearchTree() {
  this.root = null;
  // Only change code below this line
  this.invert = () => {
    if (this.root === null) {
      return;
    }
    const stack = [this.root];
    while (stack.length) {
      const node = stack.pop();
      const tmp = node.left;
      node.left = node.right;
      node.right = tmp;
      if (node.left !== null) stack.push(node.left);
      if (node.right !== null) stack.push(node.right);
    }
  };
  // Only change code above this line
}