100-room Switch

There were 100 rooms in the hotel, numbered from 1 to 100, and the first waiter opened all the room doors,
The second waiter took all the rooms numbered 2 in multiples of the "opposite treatment",
The third waiter put all the rooms numbered in multiples of 3 for "reverse treatment" ...,
This is the case in the future. Ask the 100th waiter to come after, which door is open?

#include <stdio.h>
#include <stdlib.h>

int main ()
{
int arr[101],i,j,k,arrtemp;
int t=-1;
for (k=1;k<=100;k++)
{
Arr[k]=-1; Start to OFF state
}


for (i=1;i<=100;i++)//person
{
for (j=i;j<=100;j+=i)//Room
{
ARRTEMP=-ARR[J]; Take counter
Arr[j]=arrtemp;
}
}


for (j=1;j<=100;j++)
{
if (arr[j]==1)//Room Open
{
printf ("%d,%d\n", arr[j],j);
}
}


System ("pause");
return 0;
}

100-room Switch