names$[] = [ "Baker" "Cooper" "Fletcher" "Miller" "Smith" ]
BAKER = 1
COOPER = 2
FLETCHER = 3
MILLER = 4
SMITH = 5
#
floors[] = [ 1 2 3 4 5 ]
#
proc check .
   if floors[BAKER] <> 5 and floors[COOPER] <> 1 and floors[FLETCHER] <> 1 and floors[FLETCHER] <> 5
      if floors[MILLER] > floors[COOPER] and abs (floors[SMITH] - floors[FLETCHER]) <> 1 and abs (floors[FLETCHER] - floors[COOPER]) <> 1
         for i to 5
            print names$[i] & " lives on floor " & floors[i]
         .
      .
   .
.
proc permute k .
   if k = 0
      check
      return
   .
   for i = 1 to k
      swap floors[i] floors[k]
      permute k - 1
      swap floors[k] floors[i]
   .
.
permute len floors[]