题目：

题解：

func partition(head *ListNode, x int) *ListNode {
    small := &ListNode{}
    smallHead := small
    large := &ListNode{}
    largeHead := large
    for head != nil {
        if head.Val < x {
            small.Next = head
            small = small.Next
        } else {
            large.Next = head
            large = large.Next
        }
        head = head.Next
    }
    large.Next = nil
    small.Next = largeHead.Next
    return smallHead.Next
}