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35 lines
959 B
HTML
35 lines
959 B
HTML
<p>Given the <code>root</code> of a binary tree, return <em>the preorder traversal of its nodes' values</em>.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/15/inorder_1.jpg" style="width: 125px; height: 200px;" />
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<pre>
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<strong>Input:</strong> root = [1,null,2,3]
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<strong>Output:</strong> [1,2,3]
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> root = []
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<strong>Output:</strong> []
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> root = [1]
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<strong>Output:</strong> [1]
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li>The number of nodes in the tree is in the range <code>[0, 100]</code>.</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>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?</p>
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