Aliases: quicksort3
Keywords:
### ** Examples countsort(c(2L,0L,1L,NA,2L))
[1] 0 1 2 2
countsort(c(2L,0L,1L,NA,2L), na.last=TRUE)
[1] 0 1 2 2 NA
countsort(c(2L,0L,1L,NA,2L), na.last=FALSE)
[1] NA 0 1 2 2