/**
* 各种求链表中间节点
*/
public class FindMidNode {
/**
* 输入链表头结点，奇数长度返回中点，偶数长度返回上中点
*
* @param head 头结点
* @return 中点或者上中点
*/
public Node midOrUpMidNode(Node head) {
if (head == null || head.next == null || head.next.next == null) {
return head;
}
Node slow = head.next;
Node fast = head.next.next;
while (fast.next != null && fast.next.next != null) {
slow = slow.next;
fast = fast.next.next;
}
return slow;
}
/**
* 输入链表头结点，奇数长度返回中点，偶数长度返回下中点
*
* @param head 头结点
* @return 中点或者下中点
*/
public Node midOrDownMidNode(Node head) {
if (head == null || head.next == null) {
return head;
}
Node slow = head.next;
Node fast = head.next;
while (fast.next != null && fast.next.next != null) {
slow = slow.next;
fast = fast.next.next;
}
return slow;
}
/**
* 输入链表头结点，奇数长度返回中点前一个，偶数长度返回上中点前一个
*
* @param head 头结点
* @return 结点
*/
public Node midOrUpMidPreNode(Node head) {
if (head == null || head.next == null || head.next.next == null) {
return null;
}
Node slow = head;
Node fast = head.next.next;
while (fast.next != null && fast.next.next != null) {
slow = slow.next;
fast = fast.next.next;
}
return slow;
}
/**
* 输入链表头结点，奇数长度返回中点前一个，偶数长度返回下中点前一个
*
* @param head 头结点
* @return 结点
*/
public Node midOrDownMidPreNode(Node head) {
if (head == null || head.next == null) {
return null;
}
if (head.next.next == null) {
return head;
}
Node slow = head;
Node fast = head.next;
while (fast.next != null && fast.next.next != null) {
slow = slow.next;
fast = fast.next.next;
}
return slow;
}
/**
* 链表结构
*/
public static class Node {
public int value;
public Node next;
public Node(int value) {
this.value = value;
}
}
}
/* 如有意见或建议，欢迎评论区留言；如发现代码有误，欢迎批评指正 */