[Solved] Given this simplified elevator state machine code ... Given this simplified elevator state machine code snippet, what is the final state after these events: callElevator(), arriveFloor(), openDoor()? | LLD

LLD - Design — Elevator System

Given this simplified elevator state machine code snippet, what is the final state after these events: callElevator(), arriveFloor(), openDoor()?

states = ['Idle', 'Moving', 'DoorOpen']
current_state = 'Idle'

def callElevator():
    global current_state
    if current_state == 'Idle':
        current_state = 'Moving'

def arriveFloor():
    global current_state
    if current_state == 'Moving':
        current_state = 'DoorOpen'

def openDoor():
    global current_state
    if current_state == 'DoorOpen':
        current_state = 'Idle'

AIdle

BMoving

CDoorOpen

DError

Step-by-Step Solution

Solution:

Step 1: Trace callElevator()
Starting at 'Idle', callElevator() changes state to 'Moving'.
Step 2: Trace arriveFloor() and openDoor()
arriveFloor() changes 'Moving' to 'DoorOpen', then openDoor() changes 'DoorOpen' back to 'Idle'.
Final Answer:
Idle -> Option A
Quick Check:
Idle after all events = Idle [OK]

Quick Trick: Follow state changes step-by-step [OK]

Common Mistakes:

MISTAKES

Skipping openDoor() effect
Assuming state stays at DoorOpen
Confusing event order

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More LLD Quizzes

Given this simplified elevator state machine code snippet, what is the final state after these events: callElevator(), arriveFloor(), openDoor()?

Step 1: Trace callElevator()

Step 2: Trace arriveFloor() and openDoor()

Final Answer:

Quick Check:

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