var partition = function(head, x) {
    let f = r = new ListNode();
    let p = q = head;
    //第一次遍历，将小的放进来
    while(p){
        if(p.val < x){
            let insert = new ListNode(p.val);
            r.next = insert;
            r = insert;
        }
        p = p.next;
    }
    //第二次遍历，将大的放进来
    while(q){
        if(q.val >= x){
            let insert = new ListNode(q.val);
            r.next = insert;
            r = insert;
        }
        q = q.next;
    }
    return f.next;
};