kotlin题解方法，两个变量存储

一个kotlin的题解，工作后算法相关的看的少了很多，这题居然思考了很久才解出来，用了两个变量

fun ReverseList(head: ListNode?): ListNode?  {
        var headCatch = head
        // write code here
        var headNext = headCatch?.next
        var catchNode:ListNode?=null
        while(headCatch?.next!=null){
            var nextNode = headCatch.next
            headCatch?.next = catchNode
            catchNode = headCatch
            headCatch = nextNode
        }
         var nextNode = headCatch?.next
         headCatch?.next = catchNode
         catchNode = headCatch
         headCatch = nextNode
        return catchNode
    }