Intervals - Car Pooling
Given the following code implementing the difference array approach for car pooling, what is the return value when called with trips = [[2,1,5],[3,3,7]] and capacity = 4?
Given the following code implementing the difference array approach for car pooling, what is the return value when called with trips = [[2,1,5],[3,3,7]] and capacity = 4?
easy🧾 Code Trace Q3 of Q15
Step-by-Step Solution
Solution:
Step 1: Trace diff array updates
diff[1]+=2, diff[5]-=2; diff[3]+=3, diff[7]-=3Step 2: Calculate prefix sums and check capacity
At location 3, passengers = 2 (from first trip) + 3 (second trip) = 5 > capacity 4 -> return FalseFinal Answer:
Option A -> Option AQuick Check:
Capacity exceeded at location 3 -> False [OK]
Quick Trick: Sum increments at start, decrements at end -> check capacity [OK]
Common Mistakes:
MISTAKES- Forgetting to decrement at end location
- Assuming capacity check only at trip starts
Trap Explanation:
PITFALL- Candidates often miss that passengers overlap between locations 3 and 5 causing overcapacity.
Interviewer Note:
CONTEXT- Tests ability to mentally execute difference array approach on typical input.
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