Solution (leetcode-in-java 1.23 API)

java.lang.Object
- g0301_0400.s0319_bulb_switcher.Solution

```
public class Solution
extends Object
```
319 - Bulb Switcher.
Medium

There are n bulbs that are initially off. You first turn on all the bulbs, then you turn off every second bulb.

On the third round, you toggle every third bulb (turning on if it’s off or turning off if it’s on). For the i^th round, you toggle every i bulb. For the n^th round, you only toggle the last bulb.

Return the number of bulbs that are on after n rounds.

Example 1:

Input: n = 3

Output: 1

Explanation: 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.

Example 2:

Input: n = 0

Output: 0

Example 3:

Input: n = 1

Output: 1

Constraints:
- 0 <= n <= 10⁹

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int bulbSwitch(int n)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail
- bulbSwitch
```
public int bulbSwitch(int n)
```