第二章 链表问题（在单链表和双链表中删除倒数第K个节点）

【题目】

        分别实现两个函数，一个可以删除单链表中的倒数第K个节点，另一个可以删除双链表中倒数第K个节点

public Node<Integer> deleteKthNode(Node<Integer> head, int k) {/*若节点的长度为n, 需要删除的节点就是第 n - k + 1, 需要删除的上一个节点就是第n - k个节点*/if (head == null || k < 1) {return head;}Node<Integer> cur = head;int n = 0;while (cur != null) {n++;cur = cur.next;}int preIndex = n - k;if (preIndex < 0) {return head;} else if (preIndex == 0) {return head.next;} else {cur = head;while (--preIndex != 0) {cur = cur.next;}cur.next = cur.next.next;return head;}}

DoubleNode<Integer> deleteKthDoubleNode(DoubleNode<Integer> head, int k) {/*若节点的长度为n, 需要删除的节点就是第 n - k + 1, 需要删除的上一个节点就是第n - k个节点*/if (head == null || k < 1) {return head;}DoubleNode<Integer> cur = head;int n = 0;while (cur != null) {n++;cur = cur.next;}int preIndex = n - k;if (preIndex < 0) {return head;} else if (preIndex == 0) {head.next.last = null;return head.next;} else {cur = head;while (--preIndex != 0) {cur = cur.next;}if (cur.next.next != null) {cur.next.next.last = cur;}cur.next = cur.next.next;return head;}}