{"id":385,"date":"2025-09-11T11:17:07","date_gmt":"2025-09-11T03:17:07","guid":{"rendered":"https:\/\/heyingnian.com\/?p=385"},"modified":"2025-09-11T11:17:27","modified_gmt":"2025-09-11T03:17:27","slug":"leetcode-24","status":"publish","type":"post","link":"https:\/\/heyingnian.com\/index.php\/2025\/09\/11\/leetcode-24\/","title":{"rendered":"\u4e24\u4e24\u4ea4\u6362\u94fe\u8868\u4e2d\u7684\u8282\u70b9"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">\ud83d\udd17 \u4e24\u4e24\u4ea4\u6362\u94fe\u8868\u4e2d\u7684\u8282\u70b9<\/h1>\n\n\n\n<p>\u9898\u76ee\u6765\u6e90\uff1a<a target=\"_blank\" rel=\"noreferrer noopener\"><a href=\"https:\/\/leetcode.cn\/problems\/swap-nodes-in-pairs\/description\/?envType=study-plan-v2&amp;envId=top-100-liked\" target=\"_blank\" rel=\"noopener\">24. \u4e24\u4e24\u4ea4\u6362\u94fe\u8868\u4e2d\u7684\u8282\u70b9 &#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\u4e00\u4e2a\u94fe\u8868\uff0c<strong>\u4e24\u4e24\u4ea4\u6362\u5176\u4e2d\u76f8\u90bb\u7684\u8282\u70b9<\/strong>\uff0c\u5e76\u8fd4\u56de\u4ea4\u6362\u540e\u94fe\u8868\u7684\u5934\u8282\u70b9\u3002<\/p>\n\n\n\n<p>\u8981\u6c42\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u4e0d\u80fd\u4fee\u6539\u8282\u70b9\u5185\u90e8\u7684\u503c<\/strong>\uff08\u5373\uff1a\u53ea\u80fd\u901a\u8fc7\u4fee\u6539\u6307\u9488\u8fdb\u884c\u8282\u70b9\u4ea4\u6362\uff09\u3002<\/li>\n\n\n\n<li>\u94fe\u8868\u8282\u70b9\u6570\u8303\u56f4\uff1a<code>[0, 100]<\/code><\/li>\n\n\n\n<li><code>0 &lt;= Node.val &lt;= 100<\/code><\/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-24.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"422\" height=\"222\" data-original=\"https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-24.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-386\"  sizes=\"auto, (max-width: 422px) 100vw, 422px\" \/><\/div><\/figure>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = [1,2,3,4]<\/code><br>\u8f93\u51fa\uff1a<code>[2,1,4,3]<\/code><br>\u89e3\u91ca\uff1a\u4ea4\u6362\u7b2c1\u21942\u3001\u7b2c3\u21944\u8282\u70b9\u3002<\/p>\n\n\n\n<p>\u793a\u4f8b 2\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>\u793a\u4f8b 3\uff1a<\/p>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = [1]<\/code><br>\u8f93\u51fa\uff1a<code>[1]<\/code><br>\u89e3\u91ca\uff1a\u53ea\u6709\u4e00\u4e2a\u8282\u70b9\uff0c\u65e0\u6cd5\u4ea4\u6362\uff0c\u539f\u6837\u8fd4\u56de\u3002<\/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\u7684\u6570\u76ee\u5728\u8303\u56f4\u00a0<code>[0, 100]<\/code>\u00a0\u5185<\/li>\n\n\n\n<li><code>0 &lt;= Node.val &lt;= 100<\/code><\/li>\n<\/ul>\n\n\n\n<p>\ud83d\udca1 \u89e3\u6cd5\uff1a\u865a\u62df\u5934\u8282\u70b9 + \u6307\u9488\u64cd\u4f5c \u2014\u2014 O(n) \u65f6\u95f4\uff0cO(1) \u7a7a\u95f4<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\n    public ListNode swapPairs(ListNode head) {\n        if (head == null || head.next == null) {\n            return head;\n        }\n        ListNode dummy = new ListNode(-1);\n        dummy.next = head;\n        ListNode p = dummy;\n\n        while (p.next != null &amp;&amp; p.next.next != null) {\n            ListNode first = p.next;      \n            ListNode second = p.next.next;  \n\n            \/\/ \u4e09\u6b65\u6307\u9488\u91cd\u8fde\uff1a\u4ea4\u6362 first \u548c second\n            first.next = second.next;\n            second.next = first;\n            p.next = second;\n\n            \/\/ p \u524d\u8fdb\u5230\u4e0b\u4e00\u5bf9\u8282\u70b9\u7684\u524d\u9a71\uff08\u5373\u5f53\u524d\u7684 first\uff09\n            p = first;\n        }\n\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)<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u6bcf\u4e24\u4e2a\u8282\u70b9\u5904\u7406\u4e00\u6b21\uff0c\u603b\u5171\u904d\u5386\u4e00\u6b21\u94fe\u8868\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(1) \u2705<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u4ec5\u4f7f\u7528\u5e38\u6570\u4e2a\u6307\u9488\u53d8\u91cf\uff0c\u65e0\u9012\u5f52\u3001\u65e0\u989d\u5916\u6570\u636e\u7ed3\u6784\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p>\ud83e\udde9 \u89e3\u9898\u601d\u8def<\/p>\n\n\n\n<p>\u6838\u5fc3\u601d\u60f3\uff1a\u865a\u62df\u5934\u8282\u70b9 + \u6bcf\u6b21\u4ea4\u6362\u4e00\u5bf9\u8282\u70b9\uff0c\u901a\u8fc7\u6307\u9488\u91cd\u8fde\u5b9e\u73b0\u201c\u8282\u70b9\u4ea4\u6362\u201d<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u8fb9\u754c\u5904\u7406\uff1a\n<ul class=\"wp-block-list\">\n<li>\u94fe\u8868\u4e3a\u7a7a\u6216\u53ea\u6709\u4e00\u4e2a\u8282\u70b9 \u2192 \u76f4\u63a5\u8fd4\u56de\u539f\u94fe\u8868\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u521d\u59cb\u5316\uff1a\n<ul class=\"wp-block-list\">\n<li>\u521b\u5efa\u865a\u62df\u5934\u8282\u70b9\u00a0<code>dummy<\/code>\uff0c\u6307\u5411\u00a0<code>head<\/code>\u3002<\/li>\n\n\n\n<li>\u4f7f\u7528\u6307\u9488\u00a0<code>p<\/code>\u00a0\u4f5c\u4e3a\u201c\u524d\u9a71\u6307\u9488\u201d\uff0c\u59cb\u7ec8\u6307\u5411<strong>\u5f85\u4ea4\u6362\u8282\u70b9\u5bf9\u7684\u524d\u4e00\u4e2a\u8282\u70b9<\/strong>\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u4ea4\u6362\u903b\u8f91\uff08\u5173\u952e\u4e09\u6b65\uff09\uff1a\u00a0\u5047\u8bbe\u5f53\u524d\u5f85\u4ea4\u6362\u8282\u70b9\u4e3a <code>first<\/code> \u548c <code>second<\/code>\uff1a<code>p \u2192 first \u2192 second \u2192 X<\/code>\u76ee\u6807\u53d8\u4e3a\uff1a<code>p \u2192 second \u2192 first \u2192 X<\/code>\u64cd\u4f5c\u987a\u5e8f\uff08<strong>\u5fc5\u987b\u6309\u987a\u5e8f\uff0c\u907f\u514d\u65ad\u94fe<\/strong>\uff09\uff1a\u4ea4\u6362\u903b\u8f91\uff08\u5173\u952e\u4e09\u6b65\uff09\uff1a\u00a0\u5047\u8bbe\u5f53\u524d\u5f85\u4ea4\u6362\u8282\u70b9\u4e3a <code>first<\/code> \u548c <code>second<\/code>\uff1a<code>p \u2192 first \u2192 second \u2192 X<\/code>\u76ee\u6807\u53d8\u4e3a\uff1a<code>p \u2192 second \u2192 first \u2192 X<\/code>\u64cd\u4f5c\u987a\u5e8f\uff08<strong>\u5fc5\u987b\u6309\u987a\u5e8f\uff0c\u907f\u514d\u65ad\u94fe<\/strong>\uff09\uff1a\n<ul class=\"wp-block-list\">\n<li><code>first.next = second.next<\/code>\u00a0\u2192 \u5148\u8ba9 first \u6307\u5411 second \u7684\u4e0b\u4e00\u4e2a\uff08X\uff09<\/li>\n\n\n\n<li><code>second.next = first<\/code>\u00a0\u2192 \u518d\u8ba9 second \u6307\u5411 first<\/li>\n\n\n\n<li><code>p.next = second<\/code>\u00a0\u2192 \u6700\u540e\u8ba9 p \u6307\u5411 second\uff08\u5b8c\u6210\u62fc\u63a5\uff09<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u6307\u9488\u524d\u8fdb\uff1a\n<ul class=\"wp-block-list\">\n<li><code>p = first<\/code>\uff08\u56e0\u4e3a first \u73b0\u5728\u662f\u8fd9\u4e00\u5bf9\u7684\u7b2c\u4e8c\u4e2a\u8282\u70b9\uff0c\u4e5f\u662f\u4e0b\u4e00\u5bf9\u7684\u524d\u9a71\uff09<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u5faa\u73af\u6761\u4ef6\uff1a\n<ul class=\"wp-block-list\">\n<li><code>p.next != null &amp;&amp; p.next.next != null<\/code><\/li>\n\n\n\n<li>\u786e\u4fdd\u81f3\u5c11\u8fd8\u6709\u4e24\u4e2a\u8282\u70b9\u53ef\u4ea4\u6362\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u8fd4\u56de\uff1a\n<ul class=\"wp-block-list\">\n<li><code>dummy.next<\/code>\u00a0\u4e3a\u65b0\u94fe\u8868\u5934\u8282\u70b9\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<p>\u4e3e\u4f8b\u8bf4\u660e\uff1a<\/p>\n\n\n\n<p>\u8f93\u5165\uff1a<code>head = [1,2,3,4]<\/code><\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"><code>\u521d\u59cb\uff1adummy \u2192 1 \u2192 2 \u2192 3 \u2192 4<br>          p^<br><br>\u7b2c1\u8f6e\uff1a<br>first = 1, second = 2<br>\u64cd\u4f5c\uff1a<br>1.next = 2.next \u2192 1\u21923<br>2.next = 1      \u2192 2\u21921<br>p.next = 2      \u2192 dummy\u21922\u21921\u21923\u21924<br>p = 1<br><br>\u5f53\u524d\uff1adummy \u2192 2 \u2192 1 \u2192 3 \u2192 4<br>                  p^<br><br>\u7b2c2\u8f6e\uff1a<br>first = 3, second = 4<br>\u64cd\u4f5c\uff1a<br>3.next = 4.next \u2192 3\u2192null<br>4.next = 3      \u2192 4\u21923<br>p.next = 4      \u2192 1\u21924\u21923<br>p = 3<br><br>\u6700\u7ec8\uff1adummy \u2192 2 \u2192 1 \u2192 4 \u2192 3 \u2705<br>\u8fd4\u56de dummy.next \u2192 [2,1,4,3]<\/code><\/pre>\n\n\n\n<p>\u8fb9\u754c\u5904\u7406\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7a7a\u94fe\u8868 \u2192 \u76f4\u63a5\u8fd4\u56de\u00a0<code>null<\/code><\/li>\n\n\n\n<li>\u5355\u8282\u70b9 \u2192 \u4e0d\u8fdb\u5165\u5faa\u73af\uff0c\u76f4\u63a5\u8fd4\u56de\u539f\u8282\u70b9<\/li>\n\n\n\n<li>\u5947\u6570\u4e2a\u8282\u70b9 \u2192 \u6700\u540e\u4e00\u4e2a\u8282\u70b9\u4e0d\u4ea4\u6362\uff0c\u81ea\u7136\u4fdd\u7559\uff08\u5982\u00a0<code>[1,2,3]<\/code>\u00a0\u2192\u00a0<code>[2,1,3]<\/code>\uff09<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\ud83d\udd17 \u4e24\u4e24\u4ea4\u6362\u94fe\u8868\u4e2d\u7684\u8282\u70b9 \u9898\u76ee\u6765\u6e90\uff1a24. \u4e24\u4e24\u4ea4\u6362\u94fe\u8868\u4e2d\u7684\u8282\u70b9 &#8211; \u529b\u6263\uff08LeetCode\uff09 \ud83d\udccc [&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":[14,51],"class_list":["post-385","post","type-post","status-publish","format-standard","hentry","category-algorithm","category-linked_list","tag-algorithm","tag-linked_list"],"_links":{"self":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/385","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=385"}],"version-history":[{"count":1,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/385\/revisions"}],"predecessor-version":[{"id":387,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/385\/revisions\/387"}],"wp:attachment":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/media?parent=385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/categories?post=385"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/tags?post=385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}