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37 lines
1.5 KiB
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37 lines
1.5 KiB
HTML
<p>Given the <code>root</code> of a binary tree, return <em>the same tree where every subtree (of the given tree) not containing a </em><code>1</code><em> has been removed</em>.</p>
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<p>A subtree of a node <code>node</code> is <code>node</code> plus every node that is a descendant of <code>node</code>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/06/1028_2.png" style="width: 500px; height: 140px;" />
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<pre>
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<strong>Input:</strong> root = [1,null,0,0,1]
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<strong>Output:</strong> [1,null,0,null,1]
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<strong>Explanation:</strong>
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Only the red nodes satisfy the property "every subtree not containing a 1".
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The diagram on the right represents the answer.
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</pre>
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<p><strong>Example 2:</strong></p>
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<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/06/1028_1.png" style="width: 500px; height: 115px;" />
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<pre>
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<strong>Input:</strong> root = [1,0,1,0,0,0,1]
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<strong>Output:</strong> [1,null,1,null,1]
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</pre>
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<p><strong>Example 3:</strong></p>
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<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/04/05/1028.png" style="width: 500px; height: 134px;" />
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<pre>
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<strong>Input:</strong> root = [1,1,0,1,1,0,1,0]
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<strong>Output:</strong> [1,1,0,1,1,null,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>[1, 200]</code>.</li>
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<li><code>Node.val</code> is either <code>0</code> or <code>1</code>.</li>
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</ul>
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