mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-01-11 02:58:13 +08:00
39 lines
1.4 KiB
HTML
39 lines
1.4 KiB
HTML
<p>There are <code>n</code> bulbs that are initially off. You first turn on all the bulbs, then you turn off every second bulb.</p>
|
|
|
|
<p>On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the <code>i<sup>th</sup></code> round, you toggle every <code>i</code> bulb. For the <code>n<sup>th</sup></code> round, you only toggle the last bulb.</p>
|
|
|
|
<p>Return <em>the number of bulbs that are on after <code>n</code> rounds</em>.</p>
|
|
|
|
<p> </p>
|
|
<p><strong class="example">Example 1:</strong></p>
|
|
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bulb.jpg" style="width: 421px; height: 321px;" />
|
|
<pre>
|
|
<strong>Input:</strong> n = 3
|
|
<strong>Output:</strong> 1
|
|
<strong>Explanation:</strong> At first, the three bulbs are [off, off, off].
|
|
After the first round, the three bulbs are [on, on, on].
|
|
After the second round, the three bulbs are [on, off, on].
|
|
After the third round, the three bulbs are [on, off, off].
|
|
So you should return 1 because there is only one bulb is on.</pre>
|
|
|
|
<p><strong class="example">Example 2:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> n = 0
|
|
<strong>Output:</strong> 0
|
|
</pre>
|
|
|
|
<p><strong class="example">Example 3:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> n = 1
|
|
<strong>Output:</strong> 1
|
|
</pre>
|
|
|
|
<p> </p>
|
|
<p><strong>Constraints:</strong></p>
|
|
|
|
<ul>
|
|
<li><code>0 <= n <= 10<sup>9</sup></code></li>
|
|
</ul>
|