// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/use-breadth-first-search-in-a-binary-search-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.bfs = (order) => {
    if (this.root === null) return null;
    const values = [];
    let q = [this.root];
    let nextQ = [];
    while (q.length) {
      for (let node of q) {
        values.push(node.value);
        order(node, nextQ);
      }
      q = nextQ;
      nextQ = [];
    }
    return values;
  };

  this.levelOrder = () => {
    return this.bfs((node, nextQ) => {
      if (node.left !== null) nextQ.push(node.left);
      if (node.right !== null) nextQ.push(node.right);
    });
  };

  this.reverseLevelOrder = () => {
    return this.bfs((node, nextQ) => {
      if (node.right !== null) nextQ.push(node.right);
      if (node.left !== null) nextQ.push(node.left);
    });
  };
  // Only change code above this line
}