镜像二叉树判断

const binaryTree = {
  root: {
    key: 1,
    left: {
      key: 2,
      left: { key: 3, left: {}, right: {} },
      right: { key: 4, left: {}, right: {} },
    },
    right: {
      key: 2,
      left: { key: 4, left: {}, right: {} },
      right: { key: 5, left: {}, right: {} },
    },
  },
};

##Way1
function isMirrorBinaryTree(binaryTree) {
  const nodeList = [];
  let splitArrayByTier = function (node, index) {
    if (node.key) {
      splitArrayByTier(node.left, index + 1);
      splitArrayByTier(node.right, index + 1);
      if (!nodeList[index]) nodeList[index] = [];
      nodeList[index].push(node.key);
    }
  };
  splitArrayByTier(binaryTree.root, 0);
  for (let i = 1, length = nodeList.length; i < length; i++) {
    if (JSON.stringify(nodeList[i]) !== JSON.stringify(nodeList[i].reverse())) {
      return false;
    }
  }
  return true;
}
console.log(isMirrorBinaryTree(binaryTree));

##Way2
function isMirrorBinaryTree(root) {
  if (root === null) return false;
  function isMirror(left, right) {
    if (left === null && right === null) return true;
    if (left === null || right === null) return false;
    if (left.val !== right.val) return false;
    return isMirror(left.left, right.right) && isMirror(left.right, right.left);
  }
}
console.log(isMirrorBinaryTree(binaryTree.root));