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30 lines
1.2 KiB
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30 lines
1.2 KiB
HTML
<p>Given an array of unique integers, <code>arr</code>, where each integer <code>arr[i]</code> is strictly greater than <code>1</code>.</p>
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<p>We make a binary tree using these integers, and each number may be used for any number of times. Each non-leaf node's value should be equal to the product of the values of its children.</p>
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<p>Return <em>the number of binary trees we can make</em>. The answer may be too large so return the answer <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> arr = [2,4]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> We can make these trees: <code>[2], [4], [4, 2, 2]</code></pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> arr = [2,4,5,10]
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<strong>Output:</strong> 7
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<strong>Explanation:</strong> We can make these trees: <code>[2], [4], [5], [10], [4, 2, 2], [10, 2, 5], [10, 5, 2]</code>.</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><code>1 <= arr.length <= 1000</code></li>
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<li><code>2 <= arr[i] <= 10<sup>9</sup></code></li>
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<li>All the values of <code>arr</code> are <strong>unique</strong>.</li>
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</ul>
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