Wins the offer (PHP version rewritten) ---- reconstruction of a binary tree

And enter the result in a preorder traversal of a binary tree in preorder traversal of the binary tree a rebuild. Suppose Results preorder traversal order and input of duplicate numbers are free. 
Before entering e.g. preorder traversal sequence {1,2,4,7,3,5,6,8} and {4,7,2,1,5,3,8,6} order traversal sequence, and the reconstructed binary tree return. 
the TreeNode {class 
    var $ Val; 
    var $ left = NULL; 
    var $ right = NULL; 
    function the __construct (Val $) { 
        $ this-> = $ Val Val; 
    } 
} 
Method a: built-in method without using php 
function reConstructBinaryTree ($ pre , $ VIN) 
{ 
    // Write code here Wallpaper 
    return Build (pre $, $ VIN, 0, COUNT ($ pre) -1, 0, COUNT ($ VIN) -1); 
} 

function Build (pre $, $ InOrder, Pstart $, $ PEND, ISTART $, $ IEND) { 

    IF (Pstart $> $ $ ISTART PEND ||> $ IEND) { 
        return; 
    } 
    $ $ = the root pre [$ Pstart]; 
    // root node acquired in sequence traversal subscript
    for($find = $istart; $find<=$iend;$find++){
        if($root == $inorder[$find]){
            break;
        }
    }

    $len = $find-$istart;
    $res = new TreeNode($root);
    $res->left = build($pre, $inorder, $pstart+1, $pstart+$len,$istart,$find-1);
    $res->right = build($pre, $inorder ,$pstart+$len+1, $pend,$find+1, count($inorder)-1);
    return $res;
}

$pre = [1,2,4,7,3,5,6,8];
$vin = [4,7,2,1,5,3,8,6];
print_r(reConstructBinaryTree($pre,$vin));

Method two: using php built-in methods array_search, array_slice

function reConstructBinaryTree($pre, $vin)
{
    // write code here
    if($pre && $vin){
        $treeRoot = new TreeNode($pre[0]);
        $index = array_search($pre[0],$vin);
        $treeRoot->left = reConstructBinaryTree(array_slice($pre,1,$index),array_slice($vin,0,$index));
        $treeRoot->right = reConstructBinaryTree(array_slice($pre,$index+1),array_slice($vin,$index+1));
        return $treeRoot;
    }
}