From 8f1f8d55d2d536ec0929a5f7c7b63d8c575ebeaf Mon Sep 17 00:00:00 2001 From: Wonder Date: Mon, 6 Oct 2025 11:03:21 +0800 Subject: [PATCH] =?UTF-8?q?=20=F0=9F=94=84Update:=20=E5=90=88=E5=B9=B6=20K?= =?UTF-8?q?=20=E4=B8=AA=E5=8D=87=E5=BA=8F=E9=93=BE=E8=A1=A8?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- 链表/13. 合并 K 个升序链表.md | 112 ++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 链表/13. 合并 K 个升序链表.md diff --git a/链表/13. 合并 K 个升序链表.md b/链表/13. 合并 K 个升序链表.md new file mode 100644 index 0000000..3fd7312 --- /dev/null +++ b/链表/13. 合并 K 个升序链表.md @@ -0,0 +1,112 @@ +# 合并 K 个升序链表 + +## 题目 + +给你一个链表数组,每个链表都已经按升序排列。 + +请你将所有链表合并到一个升序链表中,返回合并后的链表。 + + +示例 1: + +输入:lists = [[1,4,5],[1,3,4],[2,6]] +输出:[1,1,2,3,4,4,5,6] +解释:链表数组如下: +[ + 1->4->5, + 1->3->4, + 2->6 +] +将它们合并到一个有序链表中得到。 +1->1->2->3->4->4->5->6 +示例 2: + +输入:lists = [] +输出:[] +示例 3: + +输入:lists = [[]] +输出:[] + + +提示: + +k == lists.length +0 <= k <= 10^4 +0 <= lists[i].length <= 500 +-10^4 <= lists[i][j] <= 10^4 +lists[i] 按 升序 排列 +lists[i].length 的总和不超过 10^4 + +## 思路 + +- 分冶 + +## 代码 + +```java +/** + * Definition for singly-linked list. + * public class ListNode { + * int val; + * ListNode next; + * ListNode() {} + * ListNode(int val) { this.val = val; } + * ListNode(int val, ListNode next) { this.val = val; this.next = next; } + * } + */ +class Solution { + public ListNode mergeKLists(ListNode[] lists) { + // Special + if (lists == null || lists.length == 0) { + return null; + } + // Init: To List + List nlists = new ArrayList<>(Arrays.asList(lists)); + while (nlists.size() > 1) { + // Traverse: l1 + l2 = list + List tempList = new ArrayList<>(); + for (int i = 0; i < nlists.size(); i+=2) { + // Get l1, l2 + ListNode l1 = nlists.get(i); + ListNode l2 = null; + if (i + 1 < nlists.size()) { + l2 = nlists.get(i + 1); + } + // Merge + tempList.add(mergeTwoLists(l1, l2)); + } + nlists = tempList; + } + + return nlists.get(0); + + } + + public ListNode mergeTwoLists(ListNode list1, ListNode list2) { + // Init: DummyHead, cur + ListNode dummyHead = new ListNode(-1); + ListNode cur = dummyHead; + // Traverse: Compare + while (list1 != null && list2 != null) { + // val1 = list1.val; + // val2 = list2.val; + ListNode tmp = null; + if (list1.val > list2.val) { + tmp = list2; + list2 = list2.next; + } else { + tmp = list1; + list1 = list1.next; + } + cur.next = tmp; + cur = cur.next; + } + + cur.next = list1 == null ? list2 : list1; + + return dummyHead.next; + + } +} +``` \ No newline at end of file