solution

elevator.py

@@ -2,6 +2,7 @@
 DOWN = 2
 FLOOR_COUNT = 6
 
+
 class ElevatorLogic(object):
     """
     An incorrect implementation. Can you make it pass all the tests?
@@ -18,8 +19,16 @@ class ElevatorLogic(object):
 
     def __init__(self):
         # Feel free to add any instance variables you want.
+        self.back_for = None
+        self.back_for_direction = None
+        self.destination_direction = None
         self.destination_floor = None
         self.callbacks = None
+        self.stop_list = []
+        self.back_stop_list = []
+        self.waiting = None
+        self.trend = None
+        self.request_set = set([])
 
     def on_called(self, floor, direction):
         """
@@ -30,33 +39,120 @@ 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
+        moving_direction = 1 if self.callbacks.current_floor < self.destination_floor else 2
+        moving_further = (floor < self.destination_floor) and (moving_direction == DOWN) \
+                or (floor > self.destination_floor) and (moving_direction == UP) or not self.destination_floor
+        # moving_further = moving_further if moving_further == UP else not moving_further
+        des_change_flag = moving_further or floor == self.destination_floor
+        back_flag = (self.destination_direction != moving_direction and not self.callbacks.current_floor ==
+                     self.destination_floor) and ((self.destination_floor > self.back_for) ^ (moving_direction == UP)\
+                                                  or not self.back_for)
+        if des_change_flag or not self.destination_floor:
+            if back_flag and (floor != self.destination_floor or direction != self.destination_direction):
+                self.back_for = self.destination_floor
+                self.back_for_direction = self.destination_direction
+            if self.destination_floor in self.stop_list and (self.destination_direction != moving_direction):
+                index = self.stop_list.index(self.destination_floor)
+                self.back_stop_list.append(self.stop_list.pop(index))
+            if moving_direction != direction and moving_direction == self.destination_direction:
+                self.back_for = floor
+                self.back_for_direction = direction
+                self.back_stop_list.append(floor)
+            else:
+                self.destination_floor = floor
+                self.stop_list.append(floor)
+                self.destination_direction = direction
+        elif self.trend == UP and floor > self.callbacks.current_floor\
+                or self.trend == DOWN and floor < self.callbacks.current_floor:
+            self.destination_floor = floor
+            self.stop_list.append(floor)
+            self.destination_direction = direction
+        elif moving_direction != direction or (floor < self.callbacks.current_floor) ^ (moving_direction == DOWN) or\
+                floor == self.callbacks.current_floor:
+            self.back_for = floor
+            self.back_for_direction = direction
+            self.back_stop_list.append(floor)
+        elif direction == moving_direction:
+            self.stop_list.append(floor)
+        else:
+            self.back_stop_list.append(floor)
+        self.waiting = False
+        self.request_set.add((floor, direction))
 
     def on_floor_selected(self, floor):
+
         """
         This is called when somebody on the elevator chooses a floor.
         This could happen at any time, whether or not the elevator is moving.
         Any floor could be requested at any time.
 
         floor: the floor that was requested
         """
-        self.destination_floor = floor
+        moving_direction = 2 if self.callbacks.current_floor > self.destination_floor else 1
+        floor_to_des = 2 if floor > self.destination_floor else 1
+        des_change_flag = floor_to_des != moving_direction or self.callbacks.current_floor == self.destination_floor \
+                          or not self.destination_floor
+        back_flag = self.destination_direction and (
+            (self.destination_floor > self.back_for) ^ (moving_direction == UP)\
+                or not self.back_for) and self.callbacks.current_floor != self.destination_floor
+        if self.waiting and (self.destination_direction == DOWN) ^ (floor < self.callbacks.current_floor
+                                                                    ) and floor != self.callbacks.current_floor:
+            self.destination_direction = self.back_for_direction
+            self.destination_floor = self.back_for
+            self.stop_list.append(self.back_for)
+            # self.request_set = self.request_set.difference({(self.destination_floor, self.destination_direction)})
+            self.back_for_direction = None
+            self.back_for = None
+            if not self.destination_floor:
+                self.waiting = False
+            return
+        if des_change_flag or not self.destination_floor:
+            if back_flag:
+                self.back_for = self.destination_floor
+                self.back_for_direction = self.destination_direction
+            self.stop_list.append(floor)
+            if self.destination_floor in self.stop_list and (self.destination_direction == DOWN) ^ (
+                        self.callbacks.current_floor > self.destination_floor):
+                index = self.stop_list.index(self.destination_floor)
+                self.back_stop_list.append(self.stop_list.pop(index))
+            if floor != self.destination_floor:
+                self.destination_direction = None
+            self.destination_floor = floor
+        else:
+            self.stop_list.append(floor)
+        self.waiting = False
+        self.request_set.add((floor, None))
 
     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:
+        if self.callbacks.current_floor in self.stop_list + [1, FLOOR_COUNT]:
+            self.trend = self.callbacks.motor_direction
+            self.request_set = self.request_set.difference({(self.callbacks.current_floor, None)})
+            self.request_set = self.request_set.difference({(self.callbacks.current_floor, self.trend)})
+            if self.callbacks.current_floor == self.destination_floor and self.destination_direction:
+                self.waiting = True
             self.callbacks.motor_direction = None
+            try:
+                self.stop_list.remove(self.callbacks.current_floor)
+            except ValueError:
+                pass
 
     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
+        if self.back_for and self.callbacks.current_floor == self.destination_floor:
+            self.destination_floor = self.back_for
+            self.destination_direction = self.back_for_direction
+            self.stop_list = self.back_stop_list
+            self.back_stop_list = []
+        if self.destination_floor:
+            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