golang力扣leetcode 23.合并K个升序链表

type ListNode struct {
  Val  int
  Next *ListNode
}
func mergeKLists(lists []*ListNode) *ListNode {
  dummy := &ListNode{}
  for _, v := range lists {
    dummy.Next = merge(dummy.Next, v)
  }
  return dummy.Next
}
func merge(l1, l2 *ListNode) *ListNode {
  dummy := &ListNode{}
  cur := dummy
  for l1 != nil && l2 != nil {
    if l1.Val <= l2.Val {
      cur.Next = l1
      l1 = l1.Next
    } else {
      cur.Next = l2
      l2 = l2.Next
    }
    cur = cur.Next
  }
  for l1 != nil {
    cur.Next = l1
    l1 = l1.Next
    cur = cur.Next
  }
  for l2 != nil {
    cur.Next = l2
    l2 = l2.Next
    cur = cur.Next
  }
  return dummy.Next
}