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Update: 修复原Java版本报空指针异常(NullPointerException)
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@ -98,27 +98,33 @@ public:
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### Java:
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### Java:
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```java
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```java
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public ListNode removeNthFromEnd(ListNode head, int n){
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class Solution {
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ListNode dummyNode = new ListNode(0);
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public ListNode removeNthFromEnd(ListNode head, int n) {
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dummyNode.next = head;
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//新建一个虚拟头节点指向head
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ListNode dummyNode = new ListNode(0);
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dummyNode.next = head;
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//快慢指针指向虚拟头节点
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ListNode fastIndex = dummyNode;
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ListNode slowIndex = dummyNode;
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ListNode fastIndex = dummyNode;
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// 只要快慢指针相差 n 个结点即可
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ListNode slowIndex = dummyNode;
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for (int i = 0; i <= n; i++) {
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fastIndex = fastIndex.next;
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}
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// 只要快慢指针相差 n 个结点即可
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while (fastIndex != null) {
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for (int i = 0; i < n ; i++){
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fastIndex = fastIndex.next;
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fastIndex = fastIndex.next;
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slowIndex = slowIndex.next;
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}
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// 此时 slowIndex 的位置就是待删除元素的前一个位置。
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// 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
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// 检查 slowIndex.next 是否为 null,以避免空指针异常
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if (slowIndex.next != null) {
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slowIndex.next = slowIndex.next.next;
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}
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return dummyNode.next;
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}
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}
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while (fastIndex != null){
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fastIndex = fastIndex.next;
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slowIndex = slowIndex.next;
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}
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//此时 slowIndex 的位置就是待删除元素的前一个位置。
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//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
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slowIndex.next = slowIndex.next.next;
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return dummyNode.next;
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}
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}
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```
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```
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