Given the following state of pointers after processing intervals in the Two Pointers approach: start pointer at index 3, end pointer at index 2, and used_rooms = 2, what could be the original intervals (start and end times) that led to this state?

hard🔄 Reverse Engineer Q9 of Q15

Intervals - Meeting Rooms II (Minimum Conference Rooms)

A[[0,5],[5,10],[10,15],[15,20]]

B[[1,4],[2,5],[7,9],[8,10]]

C[[0,30],[5,10],[15,20],[25,35]]

D[[1,3],[2,4],[3,5],[4,6]]

Step-by-Step Solution

Solution:

Step 1: Understand pointer meaning
Start pointer at 3 means 3 intervals started; end pointer at 2 means 2 intervals ended; used_rooms = 2 means 1 interval still ongoing.
Step 2: Analyze options
[[0,30],[5,10],[15,20],[25,35]] intervals sorted start: [0,5,15,25], ends: [10,20,30,35]. After processing 3 starts and 2 ends, used_rooms=2 matches this scenario.
Final Answer:
Option C -> Option C
Quick Check:
Pointer positions and used_rooms consistent with [[0,30],[5,10],[15,20],[25,35]] intervals [OK]

Quick Trick: Pointer positions reflect processed starts/ends and current rooms [OK]

Common Mistakes:

MISTAKES

Misinterpreting pointer indices
Ignoring sorting order

Trap Explanation:

PITFALL

Candidates confuse pointer indices with counts or interval indices.

Interviewer Note:

CONTEXT

Tests deep understanding of Two Pointers approach internals.

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Given the following state of pointers after processing intervals in the Two Pointers approach: start pointer at index 3, end pointer at index 2, and used_rooms = 2, what could be the original intervals (start and end times) that led to this state?

Step 1: Understand pointer meaning

Step 2: Analyze options

Final Answer:

Quick Check:

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