319. Bulb Switcher

There is NBulbs that is initially off. You first turn 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 ITh round, you toggle every IBulb. For the NTh round, toggle the last bulb. Find How many bulbs is on after NRounds.

Example:

N

So you should return 1, because there are only one bulb are on.

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 Public class Solution {    publicint bulbswitch (int  n) {        //  Numbers with odd         number of divisor would be left on. // such as 1, 4, 9, ...        . return (int) math.sqrt (n);    }}

319. Bulb Switcher