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40 lines
2.1 KiB
HTML
40 lines
2.1 KiB
HTML
<p>You are given a positive integer <strong>0-indexed</strong> array <code>nums</code>.</p>
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<p>A subset of the array <code>nums</code> is <strong>square-free</strong> if the product of its elements is a <strong>square-free integer</strong>.</p>
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<p>A <strong>square-free integer</strong> is an integer that is divisible by no square number other than <code>1</code>.</p>
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<p>Return <em>the number of square-free non-empty subsets of the array</em> <strong>nums</strong>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
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<p>A <strong>non-empty</strong> <strong>subset</strong> of <code>nums</code> is an array that can be obtained by deleting some (possibly none but not all) elements from <code>nums</code>. Two subsets are different if and only if the chosen indices to delete are different.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [3,4,4,5]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> There are 3 square-free subsets in this example:
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- The subset consisting of the 0<sup>th</sup> element [3]. The product of its elements is 3, which is a square-free integer.
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- The subset consisting of the 3<sup>rd</sup> element [5]. The product of its elements is 5, which is a square-free integer.
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- The subset consisting of 0<sup>th</sup> and 3<sup>rd</sup> elements [3,5]. The product of its elements is 15, which is a square-free integer.
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It can be proven that there are no more than 3 square-free subsets in the given array.</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> nums = [1]
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<strong>Output:</strong> 1
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<strong>Explanation:</strong> There is 1 square-free subset in this example:
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- The subset consisting of the 0<sup>th</sup> element [1]. The product of its elements is 1, which is a square-free integer.
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It can be proven that there is no more than 1 square-free subset in the given array.
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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><code>1 <= nums.length <= 1000</code></li>
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<li><code>1 <= nums[i] <= 30</code></li>
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</ul>
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