All files / leetCode 0105.ts

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import { TreeNode } from './Tree'
 
export default function buildTree(
  preorder: number[],
  inorder: number[],
): TreeNode<number> | null {
  if (preorder.length === 0)
    return null
 
  const root = new TreeNode(preorder[0])
  const preorderIndex = inorder.indexOf(preorder[0])
 
  root.left = buildTree(
    preorder.slice(1, preorderIndex + 1),
    inorder.slice(0, preorderIndex),
  )
 
  root.right = buildTree(
    preorder.slice(preorderIndex + 1),
    inorder.slice(preorderIndex + 1),
  )
 
  return root
}