Emergency handling in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Emergency Handling Priorities

In an emergency handling system, which approach best ensures that the most critical emergencies are addressed first?

A Handle emergencies randomly to avoid bias.

B Assign priority levels to emergencies and always handle the highest priority first.

C Process emergencies in the order they arrive without prioritization.

D Handle only emergencies reported by senior staff.

💡 Hint

Think about how hospitals triage patients.

Assigning priority levels ensures critical emergencies get immediate attention, improving outcomes.

❓ Architecture

intermediate

Designing a Scalable Emergency Notification System

Which architecture best supports sending emergency alerts to millions of users quickly and reliably?

A A distributed message queue with multiple workers sending notifications in parallel.

B Sending notifications only during business hours to reduce load.

C Users polling the server every minute to check for emergencies.

D A single server sending notifications sequentially to each user.

💡 Hint

Think about how to handle large volumes efficiently.

A distributed message queue with parallel workers scales well and reduces delays.

❓ scaling

advanced

Estimating Capacity for Emergency Call Handling

Your emergency call center expects 10,000 calls per hour during peak times. Each call takes 3 minutes on average. How many call agents are needed to handle calls without delay?

A 500 agents

B 50 agents

C 200 agents

D 1000 agents

💡 Hint

Calculate total call minutes per hour and divide by agent availability.

10,000 calls * 3 minutes = 30,000 minutes per hour. Each agent can handle 60 minutes per hour, so 30,000 / 60 = 500 agents.

❓ tradeoff

advanced

Choosing Between Synchronous and Asynchronous Emergency Alerts

Which tradeoff is true when choosing asynchronous emergency alerts over synchronous alerts?

A Asynchronous alerts guarantee immediate delivery but use more resources.

B Synchronous alerts are always better for emergency systems.

C Synchronous alerts reduce latency but cannot handle high loads.

D Asynchronous alerts may have slight delays but improve system scalability.

💡 Hint

Consider how asynchronous processing affects speed and load.

Asynchronous alerts may delay slightly but allow the system to handle many alerts efficiently.

❓ component

expert

Identifying the Critical Component for Emergency System Reliability

Which component is most critical to ensure no emergency alert is lost in a distributed emergency handling system?

A User interface for reporting emergencies.

B Database storing user profiles.

C Persistent message queue with retry and dead-letter handling.

D Load balancer distributing requests evenly.

💡 Hint

Think about message durability and fault tolerance.

A persistent message queue with retries and dead-letter queues ensures alerts are not lost even if failures occur.

Practice

1. What is the primary goal of an emergency handling system in system design?

easy

A. To detect problems quickly and protect people and property

B. To increase system performance under normal conditions

C. To reduce the cost of hardware components

D. To provide detailed analytics for marketing purposes

Solution

1. Step 1: Understand the purpose of emergency handling

   Emergency handling systems are designed to detect issues fast and act to prevent harm.

2. Step 2: Identify the main goal

   The main goal is to protect people and property by quick detection and response.

3. Final Answer:

   To detect problems quickly and protect people and property -> Option A

4. Quick Check:

   Emergency handling = fast detection and protection [OK]

Hint: Focus on safety and speed in emergencies [OK]

Common Mistakes:

• Confusing emergency handling with performance optimization
• Thinking it is about cost reduction
• Assuming it is for marketing analytics

2. Which component is NOT typically part of an emergency handling system?

easy

A. Safety action controller

B. Alerting system

C. Detection module

D. User interface for marketing

Solution

1. Step 1: List typical components

   Emergency handling systems usually have detection, alerting, safety actions, and logging.

2. Step 2: Identify the unrelated component

   User interface for marketing is unrelated to emergency handling functions.

3. Final Answer:

   User interface for marketing -> Option D

4. Quick Check:

   Marketing UI ≠ emergency handling component [OK]

Hint: Exclude marketing from emergency system parts [OK]

Common Mistakes:

• Including unrelated business components
• Confusing alerting with marketing notifications
• Ignoring safety action controllers

3. Consider this simplified emergency system flow:
if sensor.detect(): alert.send(); safety.activate(); log.record()
What happens if sensor.detect() returns false?

medium

A. Alert, safety, and log actions all execute

B. Only alert and safety actions execute

C. No actions execute

D. Only log action executes

Solution

1. Step 1: Analyze the if condition

   The actions alert.send(), safety.activate(), and log.record() run only if sensor.detect() is true.

2. Step 2: Determine behavior when sensor.detect() is false

   If sensor.detect() returns false, the code block inside if does not run, so no actions execute.

3. Final Answer:

   No actions execute -> Option C

4. Quick Check:

   False detection = no emergency actions [OK]

Hint: If condition false means skip all inside actions [OK]

Common Mistakes:

• Assuming log always runs regardless of detection
• Thinking alert or safety run without detection
• Confusing else behavior when none is given

4. In an emergency system, this code snippet causes a problem:
if sensor.detect():
alert.send()
safety.activate()
log.record()
What is the main issue?

medium

A. Missing indentation causes log.record() to run always

B. safety.activate() is outside the if block

C. alert.send() is not called properly

D. log.record() runs even if no detection

Solution

1. Step 1: Check code indentation

   log.record() is not indented under the if, so it runs always.

2. Step 2: Understand impact

   log.record() runs even when sensor.detect() is false, which is incorrect behavior.

3. Final Answer:

   Missing indentation causes log.record() to run always -> Option A

4. Quick Check:

   Indentation controls conditional execution [OK]

Hint: Indent all emergency actions inside detection check [OK]

Common Mistakes:

• Ignoring indentation importance
• Assuming all lines are inside if by default
• Confusing which lines run conditionally

5. You design an emergency system that must alert multiple teams and log events reliably. Which design approach best ensures alerts are sent even if one alert service fails?

hard

A. Send alerts sequentially and stop on first failure

B. Send alerts in parallel with retries and fallback logging

C. Send alerts only to the primary team to reduce complexity

D. Log events only after all alerts succeed

Solution

1. Step 1: Understand reliability needs

   To ensure alerts reach multiple teams, sending in parallel avoids blocking on one failure.

2. Step 2: Use retries and fallback logging

   Retries help recover from temporary failures; fallback logging records failures for later review.

3. Final Answer:

   Send alerts in parallel with retries and fallback logging -> Option B

4. Quick Check:

   Parallel + retries = reliable alerting [OK]

Hint: Use parallel alerts with retries for reliability [OK]

Common Mistakes:

• Stopping alerts on first failure
• Ignoring retries and fallback mechanisms
• Reducing alert recipients to simplify