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41 lines
1.8 KiB
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41 lines
1.8 KiB
HTML
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<p>给定一个二叉树, 找到该树中两个指定节点的最近公共祖先。</p>
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<p><a href="https://baike.baidu.com/item/%E6%9C%80%E8%BF%91%E5%85%AC%E5%85%B1%E7%A5%96%E5%85%88/8918834?fr=aladdin" target="_blank">百度百科</a>中最近公共祖先的定义为：“对于有根树 T 的两个节点 p、q，最近公共祖先表示为一个节点 x，满足 x 是 p、q 的祖先且 x 的深度尽可能大（<strong>一个节点也可以是它自己的祖先</strong>）。”</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/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
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<pre>
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<strong>输入：</strong>root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1
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<strong>输出：</strong>3
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<strong>解释：</strong>节点 <code>5 </code>和节点 <code>1 </code>的最近公共祖先是节点 <code>3 。</code>
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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/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
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<pre>
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<strong>输入：</strong>root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4
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<strong>输出：</strong>5
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<strong>解释：</strong>节点 <code>5 </code>和节点 <code>4 </code>的最近公共祖先是节点 <code>5 。</code>因为根据定义最近公共祖先节点可以为节点本身。
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</pre>
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<p><strong>示例 3：</strong></p>
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<pre>
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<strong>输入：</strong>root = [1,2], p = 1, q = 2
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<strong>输出：</strong>1
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</pre>
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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>树中节点数目在范围 <code>[2, 10<sup>5</sup>]</code> 内。</li>
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<li><code>-10<sup>9</sup> <= Node.val <= 10<sup>9</sup></code></li>
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<li>所有 <code>Node.val</code> <code>互不相同</code> 。</li>
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<li><code>p != q</code></li>
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<li><code>p</code> 和 <code>q</code> 均存在于给定的二叉树中。</li>
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</ul>
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