LLD - Design — Elevator System
Which of the following is the correct order of servicing requests using the SCAN algorithm if the head starts at 50 and requests are at [10, 20, 35, 70, 90] with disk size 100?
Which of the following is the correct order of servicing requests using the SCAN algorithm if the head starts at 50 and requests are at [10, 20, 35, 70, 90] with disk size 100?
easy🧠 Conceptual Q12 of 15
Step-by-Step Solution
Solution:
Step 1: SCAN moves towards higher end first
Starting at 50, SCAN moves up servicing 70 and 90, then reaches disk edge 100.Step 2: SCAN reverses direction
After reaching 100, it moves down servicing 35, 20, and 10.Final Answer:
50 -> 70 -> 90 -> 100 -> 35 -> 20 -> 10 -> Option BQuick Check:
SCAN goes to edge 100 before reversing [OK]
Quick Trick: SCAN always goes to disk edge before reversing [OK]
Common Mistakes:
MISTAKES- Not including disk edge in the path
- Reversing direction too early
- Skipping requests on the way
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