Given the following pseudo-code for state transitions, what will be the final state after these events: start at idle, move up, move down, idle?

medium📝 Analysis Q13 of 15

LLD - Design — Elevator System

Given the following pseudo-code for state transitions, what will be the final state after these events: start at idle, move up, move down, idle?

state = 'idle'
if event == 'move up' and state == 'idle':
    state = 'moving up'
elif event == 'move down' and state == 'idle':
    state = 'moving down'
elif event == 'stop' and state in ['moving up', 'moving down']:
    state = 'idle'

Aerror

Bmoving down

Cmoving up

Didle

Step-by-Step Solution

Solution:

Step 1: Trace the events and state changes
Start: state = 'idle'
Event 'move up': matches first if, state = 'moving up'
Event 'move down': does not match any condition (state != 'idle', event != 'stop'), no change
Event 'idle': does not match any condition, no change. Final state = 'moving up'
Step 2: Determine final state
After all events, the state is 'moving up'.
Final Answer:
moving up -> Option C
Quick Check:
Trace confirms final state 'moving up' [OK]

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

Common Mistakes:

MISTAKES

Assuming move down changes state from moving up
Thinking event 'idle' triggers return to idle
Confusing event names with states

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Given the following pseudo-code for state transitions, what will be the final state after these events: start at idle, move up, move down, idle?

Step 1: Trace the events and state changes

Step 2: Determine final state

Final Answer:

Quick Check:

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