Given the following partial output of the greedy algorithm that sorts intervals by end time and selects non-overlapping intervals: Selected intervals end times: [3, 5, 8] Which of the following could be the original input intervals?

hard🔄 Reverse Engineer Q9 of Q15

Intervals - Non-overlapping Intervals (Max Non-Overlap)

A[[1,4],[3,5],[6,8]]

B[[1,3],[3,5],[5,8]]

C[[0,3],[2,5],[4,8]]

D[[1,2],[2,4],[4,7]]

Step-by-Step Solution

Solution:

Step 1: Check end times match selected intervals
Selected ends are 3, 5, 8, so intervals must end exactly at these times.
Step 2: Verify non-overlapping start times
[[1,3],[3,5],[5,8]] intervals start at 1,3,5 and end at 3,5,8 respectively, no overlaps.
Final Answer:
Option B -> Option B
Quick Check:
Only [[1,3],[3,5],[5,8]] matches selected end times and non-overlapping criteria [OK]

Quick Trick: Selected ends must match intervals' end times [OK]

Common Mistakes:

MISTAKES

Ignoring start times
Choosing intervals with wrong end times
Not verifying overlap

Trap Explanation:

PITFALL

Candidates often pick intervals with close but incorrect end times.

Interviewer Note:

CONTEXT

Tests ability to reverse engineer input from output state.

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More Intervals Quizzes

Given the following partial output of the greedy algorithm that sorts intervals by end time and selects non-overlapping intervals: Selected intervals end times: [3, 5, 8] Which of the following could be the original input intervals?

Step 1: Check end times match selected intervals

Step 2: Verify non-overlapping start times

Final Answer:

Quick Check:

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