package main

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func insertionSortList(head *ListNode) *ListNode {
	if head == nil || head.Next == nil {
		return head
	}
	dummy := &ListNode{}
	beg := head
	for beg != nil {
		prev := dummy
		for ; prev.Next != nil && beg.Val > prev.Next.Val; prev = prev.Next {
		}
		insert := beg
		beg = beg.Next
		insert.Next = prev.Next
		prev.Next = insert
	}
	return dummy.Next
}

// func main() {
// 	l1 := toLinkedList([]int{
// 		-1, 5, 3, 4, 0})
// 	printList(insertionSortList(l1))
// 	l2 := (*ListNode)(nil)
// 	printList(insertionSortList(l2))
// }