剑指offer--4.重建二叉树

/* function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
} */
function reConstructBinaryTree(pre, vin)
{
    var result = null;
    if(pre.length>1) {
        var root= pre[0];
        var vinrootindex = vin.indexOf(root);
        var vinleft = vin.slice(0,vinrootindex);
        var vinright = vin.slice(vinrootindex+1,vin.length);
        pre.shift();
        var preleft = pre.slice(0,vinleft.length);
        var preright = pre.slice(vinleft.length,pre.length);
        result = {
            val : root,
            left : reConstructBinaryTree(preleft,vinleft),
            right : reConstructBinaryTree(preright,vinright)
        }
    }
    else if(pre.length===1) {
        result={
            val: pre[0],
            left: null,
            right: null
        }
    }
    
    return result;
}