{"id":945,"date":"2025-12-12T19:42:46","date_gmt":"2025-12-12T11:42:46","guid":{"rendered":"https:\/\/www.guanhaobo.cn\/?p=945"},"modified":"2025-12-12T19:42:46","modified_gmt":"2025-12-12T11:42:46","slug":"leetcode-230-%e4%ba%8c%e5%8f%89%e6%90%9c%e7%b4%a2%e6%a0%91%e4%b8%ad%e7%ac%ac-k-%e5%b0%8f%e7%9a%84%e5%85%83%e7%b4%a0","status":"publish","type":"post","link":"https:\/\/www.guanhaobo.cn\/?p=945","title":{"rendered":"LeetCode 230 \u2014 \u4e8c\u53c9\u641c\u7d22\u6811\u4e2d\u7b2c K \u5c0f\u7684\u5143\u7d20"},"content":{"rendered":"<h1>\u9898\u76ee\u63cf\u8ff0<\/h1>\n<p>\u7ed9\u5b9a\u4e00\u4e2a\u4e8c\u53c9\u641c\u7d22\u6811\u7684\u6839\u8282\u70b9 root \uff0c\u548c\u4e00\u4e2a\u6574\u6570 k \uff0c\u8bf7\u4f60\u8bbe\u8ba1\u4e00\u4e2a\u7b97\u6cd5\u67e5\u627e\u5176\u4e2d\u7b2c k \u5c0f\u7684\u5143\u7d20\uff08\u4ece 1 \u5f00\u59cb\u8ba1\u6570\uff09\u3002<\/p>\n<h1>\u9898\u76ee\u5206\u6790<\/h1>\n<p>\u4e8c\u53c9\u641c\u7d22\u6811\u4e2d \u5de6 &lt; \u6839 &lt; \u53f3\uff0c\u56e0\u6b64\u76f4\u63a5\u4e2d\u5e8f\u904d\u5386\uff0c\u627e\u5230\u7b2c k \u4e2a\u88ab\u904d\u5386\u5230\u7684\u6570\u5b57\u5373\u53ef\u3002<br \/>\n\u53ef\u4ee5\u9012\u5f52\uff0c\u4e5f\u53ef\u4ee5\u7528\u6808\u8fdb\u884c\u8fed\u4ee3\u904d\u5386\u3002<\/p>\n<h1>Java<\/h1>\n<pre><code class=\"language-java line-numbers\">private int count = 0;\nprivate int ans = 0;\n\npublic int kthSmallest(TreeNode root, int k) {\n    count = 0;\n    dfs(root, k);\n    return ans;\n}\n\nprivate void dfs(TreeNode root, int k) {\n    if (root == null || count == k) {\n        return;\n    }\n    dfs(root.left, k);\n    count++;\n    if (count == k) {\n        ans = root.val;\n    }\n    dfs(root.right, k);\n}\n\npublic int kthSmallest2(TreeNode root, int k) {\n    Deque&lt;TreeNode&gt; stack = new LinkedList&lt;&gt;();\n    TreeNode cur = root;\n    int count = 0;\n    while (cur != null || !stack.isEmpty()) {\n        while (cur != null) {\n            stack.push(cur);\n            cur = cur.left;\n        }\n        cur = stack.pop();\n        count++;\n        if (count == k) {\n            break;\n        }\n        cur = cur.right;\n    }\n    return cur.val;\n}\n<\/code><\/pre>\n<h1>Kotlin<\/h1>\n<pre><code class=\"language-kotlin line-numbers\">private var count = 0\nprivate var ans = 0\n\nfun kthSmallest(root: TreeNode?, k: Int): Int {\n    count = 0\n    dfs(root, k)\n    return ans\n}\n\nprivate fun dfs(root: TreeNode?, k: Int) {\n    if (root == null || count == k) {\n        return\n    }\n    dfs(root.left, k)\n    count++\n    if (count == k) {\n        ans = root.`val`\n    }\n    dfs(root.right, k)\n}\n\nfun kthSmallest2(root: TreeNode?, k: Int): Int {\n    val stack = LinkedList&lt;TreeNode&gt;()\n    var cur = root\n    var count = 0\n    while (cur != null || !stack.isEmpty()) {\n        while (cur != null) {\n            stack.push(cur)\n            cur = cur.left\n        }\n        cur = stack.pop()\n        count++\n        if (count == k) {\n            return cur.`val`\n        }\n        cur = cur.right\n    }\n    return 0\n}\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u9898\u76ee\u63cf\u8ff0 \u7ed9\u5b9a\u4e00\u4e2a\u4e8c\u53c9\u641c\u7d22\u6811\u7684\u6839\u8282\u70b9 root \uff0c\u548c\u4e00\u4e2a\u6574\u6570 k \uff0c\u8bf7\u4f60\u8bbe\u8ba1\u4e00\u4e2a\u7b97\u6cd5\u67e5\u627e\u5176\u4e2d\u7b2c k \u5c0f\u7684\u5143\u7d20\uff08 [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[20,33,86,64],"class_list":["post-945","post","type-post","status-publish","format-standard","hentry","category-algo","tag-leetcode","tag-33","tag-86","tag-64"],"_links":{"self":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/945","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=945"}],"version-history":[{"count":1,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/945\/revisions"}],"predecessor-version":[{"id":946,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/945\/revisions\/946"}],"wp:attachment":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=945"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=945"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=945"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}