3376 - InorderTraversal

[fengjinlong]

// your answers
const tree1 = {
  val: 1,
  left: null,
  right: {
    val: 2,
    left: {
      val: 3,
      left: null,
      right: null,
    },
    right: null,
  },
} as const
interface TreeNode {
    val: number;
    left: TreeNode | null;
    right: TreeNode | null
}
type A = InorderTraversal1<typeof tree1> // [1, 3, 2]
type InorderTraversal1<T extends TreeNode | null> = [T] extends [TreeNode] ? [
    ...InorderTraversal1<T['left']>,
    T['val'],
    ...InorderTraversal1<T['right']>
]:[]

[misterhomer1992]

Hi. Could you please explain, why did you use [T] extends [TreeNode] over just T extends TreeNode, whats the point?