Class Solution
java.lang.Object
g2501_2600.s2572_count_the_number_of_square_free_subsets.Solution
2572 - Count the Number of Square-Free Subsets.<p>Medium</p>
<p>You are given a positive integer <strong>0-indexed</strong> array <code>nums</code>.</p>
<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>
<p>A <strong>square-free integer</strong> is an integer that is divisible by no square number other than <code>1</code>.</p>
<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>
<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>
<p><strong>Example 1:</strong></p>
<p><strong>Input:</strong> nums = [3,4,4,5]</p>
<p><strong>Output:</strong> 3</p>
<p><strong>Explanation:</strong> There are 3 square-free subsets in this example:</p>
<ul>
<li>
<p>The subset consisting of the 0<sup>th</sup> element [3]. The product of its elements is 3, which is a square-free integer.</p>
</li>
<li>
<p>The subset consisting of the 3<sup>rd</sup> element [5]. The product of its elements is 5, which is a square-free integer.</p>
</li>
<li>
<p>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.</p>
</li>
</ul>
<p>It can be proven that there are no more than 3 square-free subsets in the given array.</p>
<p><strong>Example 2:</strong></p>
<p><strong>Input:</strong> nums = [1]</p>
<p><strong>Output:</strong> 1</p>
<p><strong>Explanation:</strong> There is 1 square-free subset in this example:</p>
<ul>
<li>The subset consisting of the 0<sup>th</sup> element [1]. The product of its elements is 1, which is a square-free integer.</li>
</ul>
<p>It can be proven that there is no more than 1 square-free subset in the given array.</p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= nums.length <= 1000</code></li>
<li><code>1 <= nums[i] <= 30</code></li>
</ul>
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Solution
public Solution()
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Method Details
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squareFreeSubsets
public int squareFreeSubsets(int[] nums)
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