package q86

type ListNode struct {
	Val  int
	Next *ListNode
}

func partition(head *ListNode, x int) *ListNode {
	stub := &ListNode{Next: head}
	before := stub
	for before.Next != nil && before.Next.Val < x {
		before = before.Next
	}

	for p := before.Next; p != nil && p.Next != nil; {
		if p.Next.Val < x {
			move := p.Next
			p.Next = move.Next

			move.Next = before.Next
			before.Next = move
			before = move
		} else {
			p = p.Next
		}
	}
	return stub.Next
}

var _ = partition