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notes/24. 反转链表.md

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+# 24. 反转链表
+
+[NowCoder](https://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca?tpId=13&tqId=11168&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
+
+## 解题思路
+
+### 递归
+
+```java
+public ListNode ReverseList(ListNode head) {
+    if (head == null || head.next == null)
+        return head;
+    ListNode next = head.next;
+    head.next = null;
+    ListNode newHead = ReverseList(next);
+    next.next = head;
+    return newHead;
+}
+```
+
+### 迭代
+
+使用头插法。
+
+```java
+public ListNode ReverseList(ListNode head) {
+    ListNode newList = new ListNode(-1);
+    while (head != null) {
+        ListNode next = head.next;
+        head.next = newList.next;
+        newList.next = head;
+        head = next;
+    }
+    return newList.next;
+}
+```
+
+
+
+
+
+
+<div align="center"><img width="320px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/githubio/公众号二维码-1.png"></img></div>