微信图片_20211213100227.jpg

    1. var buildTree = function(preorder, inorder) {
    2.     const build = (preorder,preStart,preEnd,inorder,inStart,inEnd) =>{
    3.         if(preStart>preEnd){
    4.             return null
    5.         }
    6.         let rootval = preorder[preStart]
    7.         let index = inorder.indexOf(rootval)
    8.         let root = new TreeNode(rootval)
    9.         let leftSize = index-inStart
    10.         root.left = build(preorder,preStart+1,preStart+leftSize,inorder,inStart,index-1)
    11.         root.right = build(preorder,preStart+leftSize+1,preEnd,inorder,index+1,inEnd)
    12.         return root
    13.     }
    14.     return build(preorder,0,preorder.length-1,inorder,0,inorder.length-1)
    15. };