[Solved] Consider two approaches to find the minimum number of platforms:... When is the min-heap approach preferable over the two-pointer approach? | Greedy Algorithms

Greedy Algorithms - Minimum Platforms (Train Stations)

Consider two approaches to find the minimum number of platforms: (1) sorting arrivals and departures with two pointers, and (2) using a min-heap to track earliest departure. When is the min-heap approach preferable over the two-pointer approach?

AWhen trains have varying durations and we need to dynamically track earliest departure times

BWhen input size is very small, as min-heap has less overhead

CWhen arrival and departure times are unsorted and cannot be sorted

DWhen memory usage must be minimized, as min-heap uses less space

Step-by-Step Solution

Solution:

Step 1: Compare two-pointer and min-heap approaches
Two-pointer approach relies on sorted arrays and simple counting, efficient for fixed intervals.
Step 2: Min-heap tracks earliest departure dynamically
Min-heap is better when intervals vary and we must track platform release times dynamically, e.g., overlapping intervals with variable durations.
Final Answer:
Option A -> Option A
Quick Check:
Min-heap excels in dynamic earliest departure tracking [OK]

Quick Trick: Min-heap tracks dynamic earliest departure better [OK]

Common Mistakes:

MISTAKES

Assuming two-pointer always better
Ignoring dynamic interval durations
Confusing memory usage trade-offs

Trap Explanation:

PITFALL

Candidates often think two-pointer is always simpler, missing min-heap's dynamic tracking advantage.

Interviewer Note:

CONTEXT

Tests understanding of trade-offs between greedy approaches.

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More Greedy Algorithms Quizzes

When is the min-heap approach preferable over the two-pointer approach?

Step 1: Compare two-pointer and min-heap approaches

Step 2: Min-heap tracks earliest departure dynamically

Final Answer:

Quick Check:

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