题解 | 链表中倒数最后k个结点

/**
 * class ListNode(var `val`: Int) {
 *     var next: ListNode? = null
 * }
 */
object Solution {
    /**
    * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
    *
    * 
        * @param pHead ListNode类 
        * @param k int整型 
        * @return ListNode类
    */
    fun FindKthToTail(pHead: ListNode?,k: Int): ListNode?  {
        // write code here
        if (pHead == null || k <= 0) {
            return null
        }
        var fast:ListNode? = pHead
        var slow:ListNode? = pHead
        repeat(k){
            if (fast == null) {
                return null
            }
            fast = fast?.next
        }
        while(fast!=null){
            fast = fast?.next
            slow = slow?.next
        }
        return slow
    }
    
}