Leetcode 25. Reverse Nodes in k-Group

Reverse Nodes in k-Group.go

func reverseKGroup(head *ListNode, k int) *ListNode {
	if nil == head || k <= 1 {
		return head
	}
	dummy := &ListNode{-1, head}
	stack := make([]*ListNode, k)
	pointer := 0
	start, last := head, dummy
	for nil != start {
		stack[pointer] = start
		pointer++
		start = start.Next
		if pointer == k {
			for pointer > 0 {
				last.Next = stack[pointer-1]
				last = last.Next
				pointer--
			}
		}
	}
	for i := 0; i < pointer; i++ {
		last.Next = stack[i]
		last = last.Next
	}
	last.Next = nil
	return dummy.Next
}