; fasmg puzzle:
; find the shortest list of numbers from 1 to 13
; where each number is adjacent to every other number
;
; this also shows how to use
; sets of integers and lists of integers with many elements
;
; solution by Grom PE
;
; benchmark:
; equ list, max 180 = 2.1 seconds
; equ list, max 200 = out of memory
; dword list, max 180  = 0.2 seconds
; dword list, max 200  = 0.2 seconds
; dword list, max 2000 = 24.3 seconds
; dword list, max 4000 = 112.6 seconds (12 million elements)

macro display_int value
  temp = value
  if temp<0
    display '-'
    temp = -temp
  end if
  virtual at 0
    if temp=0
      db '0'
    end if
    while temp>0
      d = '0' + temp mod 10
      db d
      temp = temp / 10
    end while
    repeat $
      load d byte from $-%
      display d
    end repeat
  end virtual
end macro

macro set_count b
  result = 0
  if b
    rept bsr b-bsf b+1, n:bsf b
      if b and (1 shl n)
        result = result + 1
      end if
    end rept
  end if
end macro

macro set_pop b
  result = 0
  if b
    result = bsf b + 1
    b = b and not (1 shl (result-1))
  else
    err 'the set is empty'
    result = -1
  end if
end macro

max = 13
virtual at 0
rd max/2
l: dd 1 ; starting list: [1]
lap = l ; first element pointer
la = 1 ; first element value
lz = 1 ; last element value
rept max-1,n:2 ; add numbers 2 ... max
  s = 1 shl (n-1) - 1 ; set that contains numbers 1 to (n-1)
  if ~ n mod 2 ; if n is even
    ; exclude first and last list elements from the set
    s = s and not (1 shl (la-1)) and not (1 shl (lz-1))
    ; extend list from its start
    lap = lap - 4
    store n:dword at lap
    la = n
  end if
  set_count s
  if result mod 2 ; if set's length is odd
    set_pop s
    ; append to list
    dd result,n
    lz = n
  end if
  if s and (1 shl (la-1)) ; if set contains first list element
    ; exclude first and last list elements from the set
    s = s and not (1 shl (la-1)) and not (1 shl (lz-1))
    dd n,la
    lz = la
  end if
  while s
    set_pop s
    dd result,n
    set_pop s
    dd result
    lz = result
  end while
end rept
lzp:

; display the list
p = lap
while p < lzp
  load x dword from p
  if %>1
    display ' '
  end if
  display_int x
  p = p + 4
end while
end virtual