R: How to use ifelse statement for a vector of characters

Question

I am trying to solve a quiz using R, but my code does not work properly. I tried debugging, but it seems that the ifelse statement fails to work at certain numbers that seem

Answer 1

The ifelse syntax should be

switches <- rep("off", 100)
for(i in 1:100){
  k <-  seq(i, 100, i)
  switches[k] <- ifelse(switches[k] == "off",  "on", "off")
}

Answer 2

You have a binary problem. There is no reason to use ifelse. Work with logical values:

bulbs <- rep(FALSE, 100)
for (i in 1:100) bulbs[!((1:100) %% i)] <- !bulbs[!((1:100) %% i)]
which(bulbs)
#[1]   1   4   9  16  25  36  49  64  81 100