{"id":374,"date":"2025-09-09T18:33:36","date_gmt":"2025-09-09T10:33:36","guid":{"rendered":"https:\/\/heyingnian.com\/?p=374"},"modified":"2025-09-09T18:33:59","modified_gmt":"2025-09-09T10:33:59","slug":"leetcode-21","status":"publish","type":"post","link":"https:\/\/heyingnian.com\/index.php\/2025\/09\/09\/leetcode-21\/","title":{"rendered":"\u5408\u5e76\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">\ud83d\udd17 \u5408\u5e76\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">\u9898\u76ee\u6765\u6e90\uff1a<a target=\"_blank\" rel=\"noreferrer noopener\"><a href=\"https:\/\/leetcode.cn\/problems\/merge-two-sorted-lists\/?envType=study-plan-v2&amp;envId=top-100-liked\" target=\"_blank\" rel=\"noopener\">21. \u5408\u5e76\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868 &#8211; \u529b\u6263\uff08LeetCode\uff09<\/a><\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udccc \u9898\u76ee\u63cf\u8ff0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c06\u4e24\u4e2a\u5347\u5e8f\u94fe\u8868 <code>list1<\/code> \u548c <code>list2<\/code> \u5408\u5e76\u4e3a\u4e00\u4e2a\u65b0\u7684\u5347\u5e8f\u94fe\u8868\u5e76\u8fd4\u56de\u3002\u65b0\u94fe\u8868\u662f\u901a\u8fc7\u62fc\u63a5\u7ed9\u5b9a\u7684\u4e24\u4e2a\u94fe\u8868\u7684\u6240\u6709\u8282\u70b9\u7ec4\u6210\u7684\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e0d\u5141\u8bb8\u521b\u5efa\u65b0\u8282\u70b9\uff0c\u4ec5\u901a\u8fc7\u8c03\u6574\u6307\u9488\u201c\u62fc\u63a5\u201d\u539f\u6709\u8282\u70b9\u3002<\/li>\n\n\n\n<li>\u94fe\u8868\u6309\u975e\u9012\u51cf\u987a\u5e8f\u6392\u5217\uff08\u5141\u8bb8\u76f8\u7b49\uff09\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u2705 \u793a\u4f8b\u89e3\u6790<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\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-21.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"662\" height=\"302\" data-original=\"https:\/\/heyingnian.com\/wp-content\/uploads\/2025\/09\/image-21.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-375\"  sizes=\"auto, (max-width: 662px) 100vw, 662px\" \/><\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u8f93\u5165\uff1a<code>l1 = [1,2,4]<\/code>, <code>l2 = [1,3,4]<\/code><br>\u8f93\u51fa\uff1a<code>[1,1,2,3,4,4]<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u793a\u4f8b 2\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8f93\u5165\uff1a<code>l1 = []<\/code>, <code>l2 = []<\/code><br>\u8f93\u51fa\uff1a<code>[]<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u793a\u4f8b 3\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8f93\u5165\uff1a<code>l1 = []<\/code>, <code>l2 = [0]<\/code><br>\u8f93\u51fa\uff1a<code>[0]<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u26a0\ufe0f \u63d0\u793a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e24\u4e2a\u94fe\u8868\u7684\u8282\u70b9\u6570\u76ee\u8303\u56f4\u662f\u00a0<code>[0, 50]<\/code><\/li>\n\n\n\n<li><code>-100 &lt;= Node.val &lt;= 100<\/code><\/li>\n\n\n\n<li><code>l1<\/code>\u00a0\u548c\u00a0<code>l2<\/code>\u00a0\u5747\u6309\u975e\u9012\u51cf\u987a\u5e8f\u6392\u5217<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udca1 \u89e3\u6cd5\uff1a\u865a\u62df\u5934\u8282\u70b9 + \u53cc\u6307\u9488 \u2014\u2014 O(m+n) \u65f6\u95f4\uff0cO(1) \u7a7a\u95f4<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\n    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {\n        if (list1 == null) {\n            return list2;\n        }\n        if (list2 == null) {\n            return list1;\n        }\n        ListNode dummy = new ListNode(-1);\n        ListNode p = dummy;\n        while (list1 != null &amp;&amp; list2 != null) {\n            if (list1.val &lt; list2.val) {\n                p.next = list1;\n                list1 = list1.next;\n            } else {\n                p.next = list2;\n                list2 = list2.next;\n            }\n            p = p.next;\n        }\n        if (list1 == null) {\n            p.next = list2;\n        }\n        if (list2 == null) {\n            p.next = list1;\n        }\n        return dummy.next;\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udcca \u590d\u6742\u5ea6\u5206\u6790<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u65f6\u95f4\u590d\u6742\u5ea6\uff1aO(m + n)\n<ul class=\"wp-block-list\">\n<li>m\u3001n \u5206\u522b\u4e3a\u4e24\u4e2a\u94fe\u8868\u957f\u5ea6\uff0c\u6bcf\u4e2a\u8282\u70b9\u6700\u591a\u8bbf\u95ee\u4e00\u6b21\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(1) \u2705\n<ul class=\"wp-block-list\">\n<li>\u4ec5\u4f7f\u7528\u5e38\u6570\u4e2a\u989d\u5916\u6307\u9488\uff0c\u65e0\u9012\u5f52\u3001\u65e0\u54c8\u5e0c\u8868\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83e\udde9 \u89e3\u9898\u601d\u8def<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6838\u5fc3\u601d\u60f3\uff1a\u53cc\u6307\u9488\u9010\u4e2a\u6bd4\u8f83 + \u865a\u62df\u5934\u8282\u70b9\u7edf\u4e00\u5904\u7406<\/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>\u82e5\u4efb\u4e00\u94fe\u8868\u4e3a\u7a7a\uff0c\u76f4\u63a5\u8fd4\u56de\u53e6\u4e00\u4e2a\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\u7528\u4e8e\u7edf\u4e00\u64cd\u4f5c\u3002<\/li>\n\n\n\n<li>\u4f7f\u7528\u6307\u9488\u00a0<code>p<\/code>\u00a0\u8ddf\u8e2a\u5f53\u524d\u5408\u5e76\u94fe\u8868\u7684\u5c3e\u90e8\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u4e3b\u5faa\u73af\uff1a\n<ul class=\"wp-block-list\">\n<li>\u6bd4\u8f83\u00a0<code>list1<\/code>\u00a0\u548c\u00a0<code>list2<\/code>\u00a0\u5f53\u524d\u8282\u70b9\u503c\u3002<\/li>\n\n\n\n<li>\u5c06\u8f83\u5c0f\u8005\u63a5\u5230\u00a0<code>p.next<\/code>\uff0c\u5bf9\u5e94\u94fe\u8868\u6307\u9488\u524d\u79fb\u3002<\/li>\n\n\n\n<li><code>p<\/code>\u00a0\u540c\u6b65\u524d\u79fb\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u6536\u5c3e\u5904\u7406\uff1a\n<ul class=\"wp-block-list\">\n<li>\u5faa\u73af\u7ed3\u675f\u540e\uff0c\u5fc5\u6709\u4e00\u4e2a\u94fe\u8868\u672a\u904d\u5386\u5b8c\u3002<\/li>\n\n\n\n<li>\u5c06\u5269\u4f59\u90e8\u5206\u76f4\u63a5\u62fc\u63a5\u5230\u00a0<code>p.next<\/code>\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u8fd4\u56de\u7ed3\u679c\uff1a\n<ul class=\"wp-block-list\">\n<li><code>dummy.next<\/code>\u00a0\u5373\u4e3a\u5408\u5e76\u540e\u94fe\u8868\u7684\u771f\u5b9e\u5934\u8282\u70b9\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3e\u4f8b\u8bf4\u660e\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8f93\u5165\uff1a<code>l1 = [1,2,4]<\/code>, <code>l2 = [1,3,4]<\/code><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u521d\u59cb\uff1a<code>p \u2192 dummy(-1)<\/code><\/li>\n\n\n\n<li>\u7b2c1\u8f6e\uff1a<code>1(l1) vs 1(l2)<\/code>\u00a0\u2192 \u53d6\u00a0<code>l1<\/code>\u00a0\u7684 1 \u2192\u00a0<code>p \u2192 1<\/code><\/li>\n\n\n\n<li>\u7b2c2\u8f6e\uff1a<code>2(l1) vs 1(l2)<\/code>\u00a0\u2192 \u53d6\u00a0<code>l2<\/code>\u00a0\u7684 1 \u2192\u00a0<code>p \u2192 1\u21921<\/code><\/li>\n\n\n\n<li>\u7b2c3\u8f6e\uff1a<code>2 vs 3<\/code>\u00a0\u2192 \u53d6\u00a0<code>l1<\/code>\u00a0\u7684 2 \u2192\u00a0<code>p \u2192 1\u21921\u21922<\/code><\/li>\n\n\n\n<li>\u7b2c4\u8f6e\uff1a<code>4 vs 3<\/code>\u00a0\u2192 \u53d6\u00a0<code>l2<\/code>\u00a0\u7684 3 \u2192\u00a0<code>p \u2192 1\u21921\u21922\u21923<\/code><\/li>\n\n\n\n<li>\u7b2c5\u8f6e\uff1a<code>4 vs 4<\/code>\u00a0\u2192 \u53d6\u00a0<code>l2<\/code>\u00a0\u7684 4 \u2192\u00a0<code>p \u2192 1\u21921\u21922\u21923\u21924<\/code><\/li>\n\n\n\n<li><code>l2<\/code>\u00a0\u8d70\u5b8c\uff0c<code>l1<\/code>\u00a0\u5269\u4f59\u00a0<code>4<\/code>\u00a0\u2192 \u62fc\u63a5 \u2192\u00a0<code>p \u2192 ...\u21924\u21924<\/code><\/li>\n\n\n\n<li>\u8fd4\u56de\u00a0<code>dummy.next<\/code>\u00a0\u2192\u00a0<code>[1,1,2,3,4,4]<\/code>\u00a0\u2705<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fb9\u754c\u5904\u7406\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e24\u4e2a\u90fd\u4e3a\u7a7a \u2192 \u76f4\u63a5\u8fd4\u56de\u00a0<code>null<\/code>\u3002<\/li>\n\n\n\n<li>\u4e00\u4e2a\u4e3a\u7a7a \u2192 \u8fd4\u56de\u53e6\u4e00\u4e2a\u3002<\/li>\n\n\n\n<li>\u957f\u5ea6\u4e0d\u7b49 \u2192 \u5faa\u73af\u540e\u62fc\u63a5\u5269\u4f59\u90e8\u5206\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\ud83d\udd17 \u5408\u5e76\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868 \u9898\u76ee\u6765\u6e90\uff1a21. \u5408\u5e76\u4e24\u4e2a\u6709\u5e8f\u94fe\u8868 &#8211; \u529b\u6263\uff08LeetCode\uff09 \ud83d\udccc \u9898\u76ee\u63cf [&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-374","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\/374","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=374"}],"version-history":[{"count":1,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/374\/revisions"}],"predecessor-version":[{"id":376,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/374\/revisions\/376"}],"wp:attachment":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/media?parent=374"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/categories?post=374"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/tags?post=374"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}