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BulbSwitch.java
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BulbSwitch.java
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/**
* 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 nth round, you only toggle the last bulb.
* Find how many bulbs are on after n rounds.
Example:
Given n = 3.
At first, the three bulbs are [off, off, off].
After first round, the three bulbs are [on, on, on].
After second round, the three bulbs are [on, off, on].
After third round, the three bulbs are [on, off, off].
So you should return 1, because there is only one bulb is on.
*/
package com.alg.leetcode;
import java.util.Date;
public class BulbSwitch {
public static void main(String[] args) {
System.out.println(new Date());
System.out.println(bulbSwitch(4));
System.out.println(bulbSwitch(999999999));
System.out.println(new Date());
}
public static int bulbSwitch(int n) {
/*int totalOnValue=0,sqrtIntVal=0;
double sqrtDoubleVal=0;
for(int i=0;i<n;i++){
sqrtDoubleVal = Math.sqrt(i+1);
//sqrtIntVal = (int)sqrtDoubleVal;
if(sqrtDoubleVal%1==0)
totalOnValue++;
}
return totalOnValue;*/
return (int)Math.sqrt(n);
}
}