isSameBinaryTree

// Given two binary trees, write a function to check if they are equal or not.
// Two binary trees are considered equal if they are structurally identical
// and the nodes have the same value.

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} left
 * @param {TreeNode} right
 * @return {boolean}
 */
export default function isSameBinaryTree(left, right) {
  // If both is null
  if(left === null && right=== null) {
    return true;
  }
  // one null, other is not null, false
  if(left !== null && right === null || left === null && right !== null) {
    return false;
  }
  // val diff, false
  if(left.val != right.val) {
    return false;
  }
  // find next level of tree (left and right)
  return isSameBinaryTree(left.right, right.right) && isSameBinaryTree(left.left, right.left);
};