/**
 *
 * Ashish Patel
 * e: ashishsushilPatel@gmail.com
 * w: https://ashish.me
 *
 */

function TreeNode(val) {
  this.val = val
  this.left = this.right = null
}

const diameterOfBinaryTree = root => {
  if (!root) {
    return 0
  }
  let result = 0
  const traverse = root => {
    if (!root) {
      return 0
    }
    let left = traverse(root.left)
    let right = traverse(root.right)
    result = Math.max(left + right, result)
    return Math.max(left, right) + 1
  }
  traverse(root)
  return result
}

test('diameterOfBinaryTree', () => {
  const t1 = new TreeNode(1)
  t1.right = new TreeNode(3)
  t1.left = new TreeNode(2)
  t1.left.left = new TreeNode(4)
  t1.left.right = new TreeNode(5)
  expect(diameterOfBinaryTree(t1)).toEqual(3)
})