Check if a binary tree is balanced, the heights of two subtrees may never differ by more than one

isBalanced.ts

/*
Check balanced: Implement a function to check if a binary tree is balanced. For the purposes of 
this question, a balanced tree is defined to be a tree such that the heights of the two subtrees of any
node never differ by more than one.
*/

// const myTree = buildTree([1,2,3,4,5,6,7,8, 9, 10, 11, 12, 13, 14])
const myTree = new BinaryNode(1)
myTree.rightChild = new BinaryNode(2)
myTree.rightChild.rightChild = new BinaryNode(3)

function isBalanced<T>(head: BinaryNode<T>) {
  const leftHeight = getBalancedHeight(head.leftChild)
  const rightHeight = getBalancedHeight(head.rightChild)

  if (leftHeight === -1 || rightHeight === -1) return false
  return (Math.abs(leftHeight - rightHeight) <= 1)
}

function getBalancedHeight<T>(node: BinaryNode<T>) {
  if (!node) return 0

  const leftHeight = getBalancedHeight(node.leftChild)
  const rightHeight = getBalancedHeight(node.rightChild)

  if (leftHeight === -1 || rightHeight === -1) return -1
  if (Math.abs(leftHeight - rightHeight) > 1) return -1
  return Math.max(leftHeight, rightHeight) + 1
}

console.log('isBalanced', isBalanced(myTree))