nice problem :)

.gitignore

@@ -0,0 +1 @@
+*.pyc

elevator.py

@@ -1,6 +1,7 @@
 UP = 1
 DOWN = 2
 FLOOR_COUNT = 6
+OUT = 3
 
 class ElevatorLogic(object):
     """
@@ -17,9 +18,13 @@ class ElevatorLogic(object):
     """
 
     def __init__(self):
-        # Feel free to add any instance variables you want.
         self.destination_floor = None
         self.callbacks = None
+        self.destinations = []
+        for i in range(FLOOR_COUNT + 1):
+          floors = {UP: 0, DOWN: 0, OUT: 0}
+          self.destinations.append(floors)
+        self.direction = None
 
     def on_called(self, floor, direction):
         """
@@ -30,7 +35,8 @@ def on_called(self, floor, direction):
         floor: the floor that the elevator is being called to
         direction: the direction the caller wants to go, up or down
         """
-        self.destination_floor = floor
+        self.destinations[floor][direction] = 1
+        self.on_ready()
 
     def on_floor_selected(self, floor):
         """
@@ -40,23 +46,68 @@ def on_floor_selected(self, floor):
 
         floor: the floor that was requested
         """
-        self.destination_floor = floor
+        current_floor = self.callbacks.current_floor
+        if (self.direction == UP and floor <= current_floor or
+            self.direction == DOWN and floor >= current_floor):
+          return
+        self.destinations[floor][OUT] = 1
+        self.on_ready()
 
     def on_floor_changed(self):
         """
         This lets you know that the elevator has moved one floor up or down.
         You should decide whether or not you want to stop the elevator.
         """
-        if self.destination_floor == self.callbacks.current_floor:
-            self.callbacks.motor_direction = None
+        floor = self.callbacks.current_floor
+        if floor == self.destination_floor:
+          if self.destinations[floor][self.direction]:
+            self.destinations[floor][self.direction] = 0
+          elif self.destinations[floor][3 - self.direction]:
+            self.direction = 3 - self.direction
+            self.destinations[floor][self.direction] = 0
+          self.destinations[floor][OUT] = 0
+          self.callbacks.motor_direction = None
 
     def on_ready(self):
         """
         This is called when the elevator is ready to go.
         Maybe passengers have embarked and disembarked. The doors are closed,
         time to actually move, if necessary.
         """
-        if self.destination_floor > self.callbacks.current_floor:
-            self.callbacks.motor_direction = UP
-        elif self.destination_floor < self.callbacks.current_floor:
-            self.callbacks.motor_direction = DOWN
+        current_floor = self.callbacks.current_floor
+        direction, destination_floor, motor_direction = on_ready_impl(
+          current_floor, self.direction, self.destinations)
+        self.callbacks.motor_direction = motor_direction
+        self.direction = direction
+        if motor_direction == None and self.direction != None:
+          self.destinations[current_floor][OUT] = 0
+          self.destinations[current_floor][self.direction] = 0
+        self.destination_floor = destination_floor
+
+
+
+def on_ready_impl(floor, direction, destinations):
+  if direction == UP or direction is None:
+    for i in range(floor + 1, FLOOR_COUNT + 1):
+      if destinations[i][UP] or destinations[i][OUT]:
+        return UP, i, UP
+
+    for i in range(FLOOR_COUNT, floor, -1):
+      if destinations[i][DOWN]:
+        return UP, i, UP
+
+    if destinations[floor][DOWN]:
+      return DOWN, floor, None
+
+  for i in range(floor - 1, 0, -1):
+    if destinations[i][DOWN] or destinations[i][OUT]:
+      return DOWN, i, DOWN
+
+  for i in range(floor - 1, 0, -1):
+    if destinations[i][UP]:
+      return DOWN, i, DOWN
+
+  if destinations[floor][UP]:
+    return UP, floor, None
+
+  return None, None, None