RemoveNthNode
RemoveNthNode.java 源码
package datastructure.linkedlist.leetcode;
import java.util.ArrayList;
import java.util.List;
/**
* @author roseduan
* @time 2020/10/24 9:43 下午
* @description 删除链表倒数第N个节点
*/
public class RemoveNthNode {
/**
* 使用一个数组存储一下，然后再找到倒数第N个节点
*/
public ListNode removeNthFromEnd1(ListNode head, int n) {
if (head == null) {
return null;
}
List<ListNode> list = new ArrayList<>();
ListNode p = head;
while (p != null) {
list.add(p);
p = p.next;
}
if (n == list.size()) {
return head.next;
}
ListNode node = list.get(list.size() - n - 1);
node.next = node.next == null ? null : node.next.next;
return head;
}
/**
* 快慢指针法
*/
public ListNode removeNthFromEnd2(ListNode head, int n) {
if (head == null) {
return null;
}
ListNode slow = head, fast = head;
for (int i = 0; i < n; i++) {
fast = fast.next;
}
if (fast == null) {
return head.next;
}
while (fast.next != null) {
slow = slow.next;
fast = fast.next;
}
slow.next = slow.next == null ? null : slow.next.next;
return head;
}
private static class ListNode{
int val;
ListNode next;
ListNode(int val) {
this.val = val;
this.next = null;
}
}
}
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