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34 lines
1.2 KiB
HTML
34 lines
1.2 KiB
HTML
<p>给定一个二叉搜索树的根节点 <code>root</code> ，和一个整数 <code>k</code> ，请你设计一个算法查找其中第 <code>k</code><strong> </strong>小的元素（从 1 开始计数）。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2021/01/28/kthtree1.jpg" style="width: 212px; height: 301px;" />
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<pre>
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<strong>输入：</strong>root = [3,1,4,null,2], k = 1
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<strong>输出：</strong>1
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</pre>
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<p><strong>示例 2：</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2021/01/28/kthtree2.jpg" style="width: 382px; height: 302px;" />
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<pre>
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<strong>输入：</strong>root = [5,3,6,2,4,null,null,1], k = 3
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<strong>输出：</strong>3
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</pre>
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<p> </p>
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<p> </p>
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<p><strong>提示：</strong></p>
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<ul>
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<li>树中的节点数为 <code>n</code> 。</li>
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<li><code>1 <= k <= n <= 10<sup>4</sup></code></li>
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<li><code>0 <= Node.val <= 10<sup>4</sup></code></li>
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</ul>
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<p> </p>
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<p><strong>进阶：</strong>如果二叉搜索树经常被修改（插入/删除操作）并且你需要频繁地查找第 <code>k</code> 小的值，你将如何优化算法？</p>
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