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Update: 修复原Java版本报空指针异常(NullPointerException)

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beChild.pu
2024-04-09 09:47:06 +08:00
parent 872f0deec1
commit 2dce5252c0
1 changed files with 24 additions and 18 deletions
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problems/0019.删除链表的倒数第N个节点.md
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@ -98,27 +98,33 @@ public:
### Java: ### Java:
```java ```java
public ListNode removeNthFromEnd(ListNode head, int n){ class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
//新建一个虚拟头节点指向head
ListNode dummyNode = new ListNode(0); ListNode dummyNode = new ListNode(0);
dummyNode.next = head; dummyNode.next = head;
//快慢指针指向虚拟头节点
ListNode fastIndex = dummyNode; ListNode fastIndex = dummyNode;
ListNode slowIndex = dummyNode; ListNode slowIndex = dummyNode;
// 只要快慢指针相差 n 个结点即可 // 只要快慢指针相差 n 个结点即可
for (int i = 0; i < n ; i++){ for (int i = 0; i <= n; i++) {
fastIndex = fastIndex.next; fastIndex = fastIndex.next;
} }
while (fastIndex != null){ while (fastIndex != null) {
fastIndex = fastIndex.next; fastIndex = fastIndex.next;
slowIndex = slowIndex.next; slowIndex = slowIndex.next;
} }
//此时 slowIndex 的位置就是待删除元素的前一个位置。 // 此时 slowIndex 的位置就是待删除元素的前一个位置。
//具体情况可自己画一个链表长度为 3 的图来模拟代码来理解 // 具体情况可自己画一个链表长度为 3 的图来模拟代码来理解
// 检查 slowIndex.next 是否为 null，以避免空指针异常
if (slowIndex.next != null) {
slowIndex.next = slowIndex.next.next; slowIndex.next = slowIndex.next.next;
}
return dummyNode.next; return dummyNode.next;
}
} }
``` ```