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34 lines
913 B
HTML
34 lines
913 B
HTML
<p>给你二叉树的根节点 <code>root</code> ，返回其节点值 <strong>自底向上的层序遍历</strong> 。 （即按从叶子节点所在层到根节点所在的层，逐层从左向右遍历）</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/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
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<pre>
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<strong>输入：</strong>root = [3,9,20,null,null,15,7]
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<strong>输出：</strong>[[15,7],[9,20],[3]]
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</pre>
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<p><strong>示例 2：</strong></p>
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<pre>
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<strong>输入：</strong>root = [1]
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<strong>输出：</strong>[[1]]
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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 = []
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<strong>输出：</strong>[]
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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>[0, 2000]</code> 内</li>
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<li><code>-1000 <= Node.val <= 1000</code></li>
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</ul>
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