59 lines
1.4 KiB
Java
59 lines
1.4 KiB
Java
# 25. 合并两个排序的链表
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[NowCoder](https://www.nowcoder.com/practice/d8b6b4358f774294a89de2a6ac4d9337?tpId=13&tqId=11169&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
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## 题目描述
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<div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/c094d2bc-ec75-444b-af77-d369dfb6b3b4.png" width="400"/> </div><br>
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## 解题思路
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### 递归
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```java
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public ListNode Merge(ListNode list1, ListNode list2) {
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if (list1 == null)
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return list2;
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if (list2 == null)
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return list1;
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if (list1.val <= list2.val) {
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list1.next = Merge(list1.next, list2);
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return list1;
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} else {
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list2.next = Merge(list1, list2.next);
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return list2;
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}
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}
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```
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### 迭代
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```java
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public ListNode Merge(ListNode list1, ListNode list2) {
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ListNode head = new ListNode(-1);
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ListNode cur = head;
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while (list1 != null && list2 != null) {
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if (list1.val <= list2.val) {
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cur.next = list1;
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list1 = list1.next;
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} else {
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cur.next = list2;
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list2 = list2.next;
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}
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cur = cur.next;
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}
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if (list1 != null)
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cur.next = list1;
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if (list2 != null)
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cur.next = list2;
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return head.next;
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}
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```
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<div align="center"><img width="320px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/githubio/公众号二维码-2.png"></img></div>
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