카타 7급 Sum of array singles

R

repeats <- function(arr){
  sum(as.integer(names(which(table(arr)==1))))
}

repeats <- function(arr){
  2*sum(unique(arr))-sum(arr)
}

repeats <- function(arr){
  t = table(arr)
  sum(as.integer(names(t[t==1])))
}