二叉搜索树的后序遍历序列

var verifyPostorder = function(postorder) {
    if(postorder.length<=1){
        return true;
    }

    var rootVal = postorder[postorder.length-1];
    var left = [];
    var right = [];

    let i=0;
    while(postorder[i]<rootVal){//[0,i)
        left.push(postorder[i])
        i++;
    }

    while(postorder[i]!==rootVal){
        if(postorder[i]<rootVal){
            return false;
        }
        right.push(postorder[i]);
        i++;
    }
    
    return verifyPostorder(left)&&verifyPostorder(right)
};