카타 7급 Operations with sequence

R

calc <- function(arr) {
  arr[arr>0] = arr[arr>0]**2
  arr[seq_along(arr)%%3 == 0] = arr[seq_along(arr)%%3 == 0]*3
  arr[seq_along(arr)%%5 == 0] = -arr[seq_along(arr)%%5 == 0]
  sum(arr)
}

calc <- function(arr) {
  arr[arr > 0] <- arr[arr > 0] ** 2
  l = length(arr)
  if (l >= 3) {
    s = seq(3, l, 3)
    arr[s] = arr[s] * 3
  }
  if (l >= 5) {
    s = seq(5, l, 5)
    arr[s] = -arr[s]
  }
  sum(arr)
}