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Description
tab: English
<p>Write an algorithm to determine if a number <code>n</code> is happy.</p>
<p>A <strong>happy number</strong> is a number defined by the following process:</p>
<ul>
<li>Starting with any positive integer, replace the number by the sum of the squares of its digits.</li>
<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>
<li>Those numbers for which this process <strong>ends in 1</strong> are happy.</li>
</ul>
<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>
<p> </p>
<p><strong class="example">Example 1:</strong></p>
<pre>
<strong>Input:</strong> n = 19
<strong>Output:</strong> true
<strong>Explanation:</strong>
1<sup>2</sup> + 9<sup>2</sup> = 82
8<sup>2</sup> + 2<sup>2</sup> = 68
6<sup>2</sup> + 8<sup>2</sup> = 100
1<sup>2</sup> + 0<sup>2</sup> + 0<sup>2</sup> = 1
</pre>
<p><strong class="example">Example 2:</strong></p>
<pre>
<strong>Input:</strong> n = 2
<strong>Output:</strong> false
</pre>
<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= n <= 2<sup>31</sup> - 1</code></li>
</ul>
---
[submissions](https://leetcode.com/problems/happy-number/submissions/) | [solutions](https://leetcode.com/problems/happy-number/solutions/)
tab: 中文
<p>编写一个算法来判断一个数 <code>n</code> 是不是快乐数。</p>
<p><strong>「快乐数」</strong> 定义为：</p>
<ul>
<li>对于一个正整数，每一次将该数替换为它每个位置上的数字的平方和。</li>
<li>然后重复这个过程直到这个数变为 1，也可能是 <strong>无限循环</strong> 但始终变不到 1。</li>
<li>如果这个过程 <strong>结果为</strong> 1，那么这个数就是快乐数。</li>
</ul>
<p>如果 <code>n</code> 是 <em>快乐数</em> 就返回 <code>true</code> ；不是，则返回 <code>false</code> 。</p>
<p> </p>
<p><strong>示例 1：</strong></p>
<pre>
<strong>输入：</strong>n = 19
<strong>输出：</strong>true
<strong>解释：
</strong>1<sup>2</sup> + 9<sup>2</sup> = 82
8<sup>2</sup> + 2<sup>2</sup> = 68
6<sup>2</sup> + 8<sup>2</sup> = 100
1<sup>2</sup> + 0<sup>2</sup> + 0<sup>2</sup> = 1
</pre>
<p><strong>示例 2：</strong></p>
<pre>
<strong>输入：</strong>n = 2
<strong>输出：</strong>false
</pre>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li><code>1 <= n <= 2<sup>31</sup> - 1</code></li>
</ul>
---
[提交记录](https://leetcode.cn/problems/happy-number/submissions/) | [题解](https://leetcode.cn/problems/happy-number/solution/)
Solutions & Notes
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