{"id":420,"date":"2025-09-28T16:47:31","date_gmt":"2025-09-28T08:47:31","guid":{"rendered":"https:\/\/heyingnian.com\/?p=420"},"modified":"2025-09-28T16:47:50","modified_gmt":"2025-09-28T08:47:50","slug":"leetcode-101","status":"publish","type":"post","link":"https:\/\/heyingnian.com\/index.php\/2025\/09\/28\/leetcode-101\/","title":{"rendered":"\u5bf9\u79f0\u4e8c\u53c9\u6811"},"content":{"rendered":"\n

\ud83d\udd17 \u5bf9\u79f0\u4e8c\u53c9\u6811<\/h1>\n\n\n\n

\u9898\u76ee\u6765\u6e90\uff1a101. \u5bf9\u79f0\u4e8c\u53c9\u6811 – \u529b\u6263\uff08LeetCode\uff09<\/a><\/p>\n\n\n\n

\ud83d\udccc \u9898\u76ee\u63cf\u8ff0<\/p>\n\n\n\n

\u7ed9\u4f60\u4e00\u4e2a\u4e8c\u53c9\u6811\u7684\u6839\u8282\u70b9 root<\/code>\uff0c\u68c0\u67e5\u5b83\u662f\u5426\u8f74\u5bf9\u79f0<\/strong>\u3002<\/p>\n\n\n\n

\u5373\uff1a\u4e8c\u53c9\u6811\u662f\u5426\u4ee5\u6839\u8282\u70b9\u4e3a\u4e2d\u5fc3\uff0c\u5de6\u53f3\u4e24\u68f5\u5b50\u6811\u4e92\u4e3a\u955c\u50cf\u3002<\/p>\n\n\n\n

\u2705 \u793a\u4f8b\u89e3\u6790<\/p>\n\n\n\n

\u793a\u4f8b 1\uff1a<\/strong><\/p>\n\n\n\n

\"\"<\/div><\/figure>\n\n\n\n

\u8f93\u5165\uff1aroot = [1,2,2,3,4,4,3]<\/code>
\u8f93\u51fa\uff1atrue<\/code>
\u89e3\u91ca\uff1a\u5de6\u5b50\u6811 [2,3,4]<\/code> \u4e0e\u53f3\u5b50\u6811 [2,4,3]<\/code> \u4e92\u4e3a\u955c\u50cf\uff0c\u6574\u4f53\u7ed3\u6784\u5bf9\u79f0\u3002<\/p>\n\n\n\n

\u793a\u4f8b 2\uff1a<\/strong><\/p>\n\n\n\n

\"\"<\/div><\/figure>\n\n\n\n

\u8f93\u5165\uff1aroot = [1,2,2,null,3,null,3]<\/code>
\u8f93\u51fa\uff1afalse<\/code>
\u89e3\u91ca\uff1a\u5de6\u5b50\u6811\u4e3a [2,null,3]<\/code>\uff0c\u53f3\u5b50\u6811\u4e3a [2,null,3]<\/code>\uff0c\u4f46\u4f4d\u7f6e\u4e0d\u5bf9\u79f0\uff08\u5de6\u5b50\u6811\u7684\u53f3\u5b69\u5b50 vs \u53f3\u5b50\u6811\u7684\u53f3\u5b69\u5b50\uff09\uff0c\u4e0d\u6ee1\u8db3\u955c\u50cf\u6761\u4ef6\u3002<\/p>\n\n\n\n

\u793a\u4f8b 3\uff1a<\/strong><\/p>\n\n\n\n

\u8f93\u5165\uff1aroot = [1]<\/code>
\u8f93\u51fa\uff1atrue<\/code>
\u89e3\u91ca\uff1a\u5355\u4e2a\u8282\u70b9\u5929\u7136\u5bf9\u79f0\u3002<\/p>\n\n\n\n

\u26a0\ufe0f \u63d0\u793a<\/p>\n\n\n\n

    \n
  • \u6811\u4e2d\u8282\u70b9\u6570\u76ee\u5728\u8303\u56f4\u00a0[1, 1000]<\/code>\u00a0\u5185<\/li>\n\n\n\n
  • -100 <= Node.val <= 100<\/code><\/li>\n<\/ul>\n\n\n\n

    \ud83d\udca1 \u89e3\u6cd5\uff1a\u9012\u5f52\uff08\u53cc\u6307\u9488\u955c\u50cf\u6bd4\u8f83\uff09\u2014\u2014 O(n) \u65f6\u95f4\uff0cO(h) \u7a7a\u95f4<\/p>\n\n\n\n

    class Solution {\n    public boolean isSymmetric(TreeNode root) {\n        return dfs(root.left, root.right);\n    }\n\n    public boolean dfs(TreeNode left, TreeNode right) {\n        if (left == null && right == null) {\n            return true;\n        }\n        if (left == null || right == null || left.val != right.val) {\n            return false;\n        }\n        return dfs(left.left, right.right) && dfs(left.right, right.left);\n    }\n}<\/code><\/pre>\n\n\n\n
    \ud83d\udcca \u590d\u6742\u5ea6\u5206\u6790<\/p>\n\n\n\n
      \n
    • \u65f6\u95f4\u590d\u6742\u5ea6\uff1aO(n)<\/strong>
      \u6700\u574f\u60c5\u51b5\u4e0b\u9700\u8981\u904d\u5386\u6240\u6709\u8282\u70b9\uff08\u6bcf\u4e2a\u8282\u70b9\u88ab\u8bbf\u95ee\u4e00\u6b21\uff09\uff0c\u56e0\u6b64\u65f6\u95f4\u590d\u6742\u5ea6\u4e3a O(n)\u3002<\/li>\n\n\n\n
    • \u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(h)<\/strong>
      \u9012\u5f52\u8c03\u7528\u6808\u7684\u6df1\u5ea6\u53d6\u51b3\u4e8e\u6811\u7684\u9ad8\u5ea6 h\u3002\u6700\u574f\u60c5\u51b5\uff08\u94fe\u72b6\u6811\uff09\u4e3a O(n)\uff0c\u5e73\u5747\u60c5\u51b5\uff08\u5e73\u8861\u6811\uff09\u4e3a O(log n)\u3002<\/li>\n<\/ul>\n\n\n\n
      \ud83e\udde9 \u89e3\u9898\u601d\u8def<\/p>\n\n\n\n
      \u6838\u5fc3\u601d\u60f3\uff1a\u955c\u50cf\u5bf9\u6bd4<\/strong>
      \u5224\u65ad\u4e00\u68f5\u6811\u662f\u5426\u5bf9\u79f0\uff0c\u7b49\u4ef7\u4e8e\u5224\u65ad\u5b83\u7684\u5de6\u5b50\u6811\u548c\u53f3\u5b50\u6811\u662f\u5426\u4e92\u4e3a\u955c\u50cf<\/strong>\u3002<\/p>\n\n\n\n
      \u5982\u4f55\u5224\u65ad\u4e24\u68f5\u6811\u4e92\u4e3a\u955c\u50cf\uff1f<\/strong><\/p>\n\n\n\n
        \n
      1. \u5b83\u4eec\u7684\u6839\u8282\u70b9\u503c\u76f8\u7b49\uff1b<\/li>\n\n\n\n
      2. \u7b2c\u4e00\u68f5\u6811\u7684\u5de6\u5b50\u6811 \u4e0e \u7b2c\u4e8c\u68f5\u6811\u7684\u53f3\u5b50\u6811 \u5bf9\u79f0\uff1b<\/li>\n\n\n\n
      3. \u7b2c\u4e00\u68f5\u6811\u7684\u53f3\u5b50\u6811 \u4e0e \u7b2c\u4e8c\u68f5\u6811\u7684\u5de6\u5b50\u6811 \u5bf9\u79f0\u3002<\/li>\n<\/ol>\n\n\n\n
        \u8fd9\u5929\u7136\u9002\u5408\u7528\u9012\u5f52<\/strong>\u5b9e\u73b0\u3002<\/p>\n\n\n\n
        \u9012\u5f52\u7ec8\u6b62\u6761\u4ef6\uff1a<\/strong><\/p>\n\n\n\n
          \n
        • \u4e24\u4e2a\u8282\u70b9\u90fd\u4e3a\u7a7a \u2192 \u5bf9\u79f0 \u2705<\/li>\n\n\n\n
        • \u5176\u4e2d\u4e00\u4e2a\u4e3a\u7a7a\u6216\u503c\u4e0d\u7b49 \u2192 \u4e0d\u5bf9\u79f0 \u274c<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
          \ud83d\udd17 \u5bf9\u79f0\u4e8c\u53c9\u6811 \u9898\u76ee\u6765\u6e90\uff1a101. \u5bf9\u79f0\u4e8c\u53c9\u6811 – \u529b\u6263\uff08LeetCode\uff09 \ud83d\udccc \u9898\u76ee\u63cf\u8ff0 \u7ed9\u4f60\u4e00 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[39,12],"tags":[57,58,14],"class_list":["post-420","post","type-post","status-publish","format-standard","hentry","category-binary_tree","category-algorithm","tag-binary_tree","tag-dfs","tag-algorithm"],"_links":{"self":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/420","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=420"}],"version-history":[{"count":1,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/420\/revisions"}],"predecessor-version":[{"id":423,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/420\/revisions\/423"}],"wp:attachment":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/media?parent=420"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/categories?post=420"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/tags?post=420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}