quick_sort.nim

discard """
Run as following.
  $ nim c -r --verbosity:0 quick_sort.nim
"""


proc sort(alist: var seq[int]): seq[int] =
  if alist.len == 0:
    return alist

  var
    pivot = alist[0]

  var
    left:   seq[int] = @[]
    right:  seq[int] = @[]

  for i in 1..alist.len-1:
    if pivot <= alist[i]:
      right.add(alist[i])
    else:
      left.add(alist[i])

  left = sort(left)
  right = sort(right)

  var total = left & @[pivot] & right

  return total


var alist = @[2, 4, 5, 0, 1]
echo(sort(alist))