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52 lines
1.3 KiB
HTML
52 lines
1.3 KiB
HTML
<p>给你二叉树的根节点 <code>root</code> ，返回它节点值的 <strong>前序</strong><em> </em>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/2020/09/15/inorder_1.jpg" style="width: 202px; height: 324px;" />
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<pre>
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<strong>输入：</strong>root = [1,null,2,3]
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<strong>输出：</strong>[1,2,3]
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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 = []
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<strong>输出：</strong>[]
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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]
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<strong>输出：</strong>[1]
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</pre>
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<p><strong>示例 4：</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_5.jpg" style="width: 202px; height: 202px;" />
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<pre>
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<strong>输入：</strong>root = [1,2]
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<strong>输出：</strong>[1,2]
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</pre>
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<p><strong>示例 5：</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_4.jpg" style="width: 202px; height: 202px;" />
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<pre>
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<strong>输入：</strong>root = [1,null,2]
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<strong>输出：</strong>[1,2]
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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, 100]</code> 内</li>
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<li><code>-100 <= Node.val <= 100</code></li>
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</ul>
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<p> </p>
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<p><strong>进阶：</strong>递归算法很简单，你可以通过迭代算法完成吗？</p>
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