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39 lines
1.2 KiB
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39 lines
1.2 KiB
HTML
<p>Write an algorithm to determine if a number <code>n</code> is happy.</p>
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<p>A <strong>happy number</strong> is a number defined by the following process:</p>
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<ul>
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<li>Starting with any positive integer, replace the number by the sum of the squares of its digits.</li>
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<li>Repeat the process until the number equals 1 (where it will stay), or it <strong>loops endlessly in a cycle</strong> which does not include 1.</li>
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<li>Those numbers for which this process <strong>ends in 1</strong> are happy.</li>
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</ul>
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<p>Return <code>true</code> <em>if</em> <code>n</code> <em>is a happy number, and</em> <code>false</code> <em>if not</em>.</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> n = 19
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<strong>Output:</strong> true
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<strong>Explanation:</strong>
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1<sup>2</sup> + 9<sup>2</sup> = 82
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8<sup>2</sup> + 2<sup>2</sup> = 68
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6<sup>2</sup> + 8<sup>2</sup> = 100
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1<sup>2</sup> + 0<sup>2</sup> + 0<sup>2</sup> = 1
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> n = 2
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<strong>Output:</strong> false
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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 <= n <= 2<sup>31</sup> - 1</code></li>
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</ul>
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