{"id":398,"date":"2025-09-16T18:19:11","date_gmt":"2025-09-16T10:19:11","guid":{"rendered":"https:\/\/heyingnian.com\/?p=398"},"modified":"2025-09-16T18:20:52","modified_gmt":"2025-09-16T10:20:52","slug":"leetcode-148","status":"publish","type":"post","link":"https:\/\/heyingnian.com\/index.php\/2025\/09\/16\/leetcode-148\/","title":{"rendered":"\u6392\u5e8f\u94fe\u8868"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">\ud83d\udd17 \u6392\u5e8f\u94fe\u8868<\/h1>\n\n\n\n<p>\u9898\u76ee\u6765\u6e90\uff1a<a target=\"_blank\" rel=\"noreferrer noopener\"><a href=\"https:\/\/leetcode.cn\/problems\/sort-list\/description\/?envType=study-plan-v2&amp;envId=top-100-liked\" target=\"_blank\" rel=\"noopener\">148. \u6392\u5e8f\u94fe\u8868 &#8211; \u529b\u6263\uff08LeetCode\uff09<\/a><\/a><\/p>\n\n\n\n<p>\ud83d\udccc \u9898\u76ee\u63cf\u8ff0<\/p>\n\n\n\n<p>\u7ed9\u4f60\u94fe\u8868\u7684\u5934\u8282\u70b9 <code>head<\/code>\uff0c\u8bf7\u5c06\u5176\u6309<strong>\u5347\u5e8f\u6392\u5217<\/strong>\u5e76\u8fd4\u56de\u6392\u5e8f\u540e\u7684\u94fe\u8868\u3002<\/p>\n\n\n\n<p>\u8981\u6c42\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u65f6\u95f4\u590d\u6742\u5ea6\uff1aO(n log n)<\/strong><\/li>\n\n\n\n<li><strong>\u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(log n)<\/strong>\uff08\u9012\u5f52\u6808\u7a7a\u95f4\uff0c\u7b26\u5408\u201c\u5e38\u6570\u7ea7\u989d\u5916\u7a7a\u95f4\u201d\u7684\u5bbd\u677e\u89e3\u91ca\uff09<\/li>\n\n\n\n<li>\u4e0d\u80fd\u8f6c\u6362\u6210\u6570\u7ec4\u6392\u5e8f\u518d\u91cd\u5efa\u94fe\u8868\uff08\u8003\u5bdf\u94fe\u8868\u539f\u5730\u64cd\u4f5c\u80fd\u529b\uff09<\/li>\n<\/ul>\n\n\n\n<p>\u2705 \u793a\u4f8b\u89e3\u6790<\/p>\n\n\n\n<p>\u793a\u4f8b 1\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-30.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"562\" height=\"242\" data-original=\"https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-30.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-399\"  sizes=\"auto, (max-width: 562px) 100vw, 562px\" \/><\/div><\/figure>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = [4,2,1,3]<\/code><br>\u8f93\u51fa\uff1a<code>[1,2,3,4]<\/code><\/p>\n\n\n\n<p>\u793a\u4f8b 2\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-31.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"722\" height=\"242\" data-original=\"https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-31.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-400\"  sizes=\"auto, (max-width: 722px) 100vw, 722px\" \/><\/div><\/figure>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = [-1,5,3,4,0]<\/code><br>\u8f93\u51fa\uff1a<code>[-1,0,3,4,5]<\/code><\/p>\n\n\n\n<p>\u793a\u4f8b 3\uff1a<\/p>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = []<\/code><br>\u8f93\u51fa\uff1a<code>[]<\/code><\/p>\n\n\n\n<p>\u26a0\ufe0f \u63d0\u793a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u94fe\u8868\u4e2d\u8282\u70b9\u6570\u76ee\u8303\u56f4\uff1a<code>[0, 5 * 10\u2074]<\/code><\/li>\n\n\n\n<li><code>Node.val<\/code>&nbsp;\u8303\u56f4\uff1a<code>[-10\u2075, 10\u2075]<\/code><\/li>\n<\/ul>\n\n\n\n<p>\ud83d\udca1 \u89e3\u6cd5\uff1a\u81ea\u9876\u5411\u4e0b\u5f52\u5e76\u6392\u5e8f\uff08Top-Down Merge Sort\uff09\u2014\u2014 O(n log n) \u65f6\u95f4\uff0cO(log n) \u7a7a\u95f4<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\n    public ListNode sortList(ListNode head) {\n        if (head == null || head.next == null) {\n            return head;\n        }\n\n        ListNode mid = middleNode(head);\n        ListNode rightHead = mid.next;\n        mid.next = null;\n\n        ListNode left = sortList(head);\n        ListNode right = sortList(rightHead);\n\n        return merge(left, right);\n    }\n\n    private ListNode middleNode(ListNode head) {\n        ListNode slow = head;\n        ListNode fast = head.next;\n\n        while (fast != null &amp;&amp; fast.next != null) {\n            slow = slow.next;\n            fast = fast.next.next;\n        }\n\n        return slow;\n    }\n\n    private ListNode merge(ListNode l1, ListNode l2) {\n        ListNode dummy = new ListNode(-1);\n        ListNode curr = dummy;\n\n        while (l1 != null &amp;&amp; l2 != null) {\n            if (l1.val &lt; l2.val) {\n                curr.next = l1;\n                l1 = l1.next;\n            } else {\n                curr.next = l2;\n                l2 = l2.next;\n            }\n            curr = curr.next;\n        }\n\n        curr.next = l1 != null ? l1 : l2;\n        return dummy.next;\n    }\n}<\/code><\/pre>\n\n\n\n<p>\ud83d\udcca \u590d\u6742\u5ea6\u5206\u6790<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u65f6\u95f4\u590d\u6742\u5ea6\uff1aO(n log n) \u2705<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u5206\uff1a\u6bcf\u6b21\u627e\u4e2d\u70b9 O(n)\uff0c\u5171 log n \u5c42 \u2192 \u603b O(n log n)<\/li>\n\n\n\n<li>\u6cbb\uff1a\u6bcf\u5c42\u5408\u5e76\u603b\u957f\u4e3a n\uff0c\u5171 log n \u5c42 \u2192 \u603b O(n log n)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(log n)<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u9012\u5f52\u8c03\u7528\u6808\u6df1\u5ea6\u4e3a log n\uff08\u94fe\u8868\u957f\u5ea6\u6bcf\u6b21\u51cf\u534a\uff09<\/li>\n\n\n\n<li>\u7b26\u5408\u9898\u76ee\u201c\u5e38\u6570\u7ea7\u989d\u5916\u7a7a\u95f4\u201d\u7684\u5bbd\u677e\u8981\u6c42\uff08\u5bf9\u6bd4\u6570\u7ec4\u5f52\u5e76\u7684 O(n)\uff09<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u26a0\ufe0f \u6ce8\uff1a\u82e5\u8981\u6c42 <strong>\u4e25\u683c O(1) \u7a7a\u95f4<\/strong>\uff0c\u9700\u4f7f\u7528\u201c\u81ea\u5e95\u5411\u4e0a\u5f52\u5e76\u6392\u5e8f\u201d\uff0c\u4f46\u4ee3\u7801\u590d\u6742\uff0c\u9762\u8bd5\u4e2d\u672c\u89e3\u6cd5\u5df2\u8db3\u591f\u3002<\/p>\n<\/blockquote>\n\n\n\n<p>\ud83e\udde9 \u89e3\u9898\u601d\u8def<\/p>\n\n\n\n<p>\u6838\u5fc3\u601d\u60f3\uff1a<strong>\u5206\u6cbb\u6cd5\uff08Divide and Conquer\uff09 + \u5f52\u5e76\u6392\u5e8f<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u9012\u5f52\u7ec8\u6b62\u6761\u4ef6\uff1a\n<ul class=\"wp-block-list\">\n<li><code>head == null<\/code>&nbsp;\u6216&nbsp;<code>head.next == null<\/code>&nbsp;\u2192 \u65e0\u9700\u6392\u5e8f\uff0c\u76f4\u63a5\u8fd4\u56de\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u5206 \u2014\u2014 \u627e\u4e2d\u70b9 &amp; \u65ad\u94fe\uff1a\n<ul class=\"wp-block-list\">\n<li>\u4f7f\u7528<strong>\u5feb\u6162\u6307\u9488<\/strong>\u627e\u4e2d\u70b9\uff08<code>slow<\/code>&nbsp;\u548c&nbsp;<code>fast<\/code>\uff09\u3002<\/li>\n\n\n\n<li><code>fast = head.next<\/code>&nbsp;\u2192 \u4fdd\u8bc1\u5076\u6570\u8282\u70b9\u65f6\uff0c<code>slow<\/code>&nbsp;\u505c\u5728<strong>\u5de6\u4e2d\u70b9<\/strong>\uff08\u5982 4 \u4e2a\u8282\u70b9\u505c\u5728\u7b2c 2 \u4e2a\uff09\u3002<\/li>\n\n\n\n<li><code>midNode.next = null<\/code>&nbsp;\u2192 \u5c06\u94fe\u8868\u4ece\u4e2d\u95f4\u65ad\u5f00\uff0c\u5206\u6210&nbsp;<code>head<\/code>&nbsp;\u5230&nbsp;<code>midNode<\/code>&nbsp;\u548c&nbsp;<code>rightHead<\/code>&nbsp;\u5f00\u5934\u7684\u4e24\u90e8\u5206\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u6cbb \u2014\u2014 \u9012\u5f52\u6392\u5e8f\uff1a\n<ul class=\"wp-block-list\">\n<li><code>left = sortList(head)<\/code>&nbsp;\u2192 \u9012\u5f52\u6392\u5e8f\u5de6\u534a\u90e8\u5206<\/li>\n\n\n\n<li><code>right = sortList(rightHead)<\/code>&nbsp;\u2192 \u9012\u5f52\u6392\u5e8f\u53f3\u534a\u90e8\u5206<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u5408 \u2014\u2014 \u5408\u5e76\u6709\u5e8f\u94fe\u8868\uff1a\n<ul class=\"wp-block-list\">\n<li>\u8c03\u7528&nbsp;<code>mergeTwoLists(left, right)<\/code>\uff0c\u5c06\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868\u5408\u5e76\u6210\u4e00\u4e2a\u6709\u5e8f\u94fe\u8868\u3002<\/li>\n\n\n\n<li>\u4f7f\u7528\u54e8\u5175\u8282\u70b9\u00a0<code>dummy<\/code>\u00a0\u7b80\u5316\u5934\u8282\u70b9\u5904\u7406\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u8fd4\u56de\u5408\u5e76\u7ed3\u679c\u3002<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\ud83d\udd17 \u6392\u5e8f\u94fe\u8868 \u9898\u76ee\u6765\u6e90\uff1a148. \u6392\u5e8f\u94fe\u8868 &#8211; \u529b\u6263\uff08LeetCode\uff09 \ud83d\udccc \u9898\u76ee\u63cf\u8ff0 \u7ed9\u4f60\u94fe\u8868\u7684 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,38],"tags":[16,55,33,51],"class_list":["post-398","post","type-post","status-publish","format-standard","hentry","category-algorithm","category-linked_list","tag-double_pointers","tag-merge_sort","tag-sorting","tag-linked_list"],"_links":{"self":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/398","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/comments?post=398"}],"version-history":[{"count":2,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/398\/revisions"}],"predecessor-version":[{"id":402,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/398\/revisions\/402"}],"wp:attachment":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/media?parent=398"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/categories?post=398"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/tags?post=398"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}