[Solved] Consider this buggy code snippet for removing covered intervals: def remove_covered_intervals(intervals): intervals.sort(key=lambda x:... | Intervals

Intervals - Remove Covered Intervals

Consider this buggy code snippet for removing covered intervals:

def remove_covered_intervals(intervals):
    intervals.sort(key=lambda x: (x[0], x[1]))  # Bug here
    count = 0
    max_end = 0
    for _, end in intervals:
        if end > max_end:
            count += 1
            max_end = end
    return count

What is the bug in this code?

AThe condition 'if end > max_end' should be 'if end >= max_end' to include equal ends.

Bmax_end is not updated correctly inside the loop.

CSorting by end ascending instead of descending causes coverage detection failure.

DThe nested loop for coverage check is missing, causing incorrect results.

Step-by-Step Solution

Step 1: Analyze sorting key
Sorting by (start ascending, end ascending) orders intervals with same start from shortest to longest, which breaks coverage detection.
Step 2: Understand coverage detection logic
Coverage detection relies on intervals with same start being sorted longest first (end descending) so covered intervals come after.
Final Answer:
Option C -> Option C
Quick Check:
Sorting end ascending causes missed coverage when starts equal [OK]

Quick Trick: Sort end descending to detect coverage correctly [OK]

Common Mistakes:

MISTAKES

Sorting end ascending instead of descending
Using strict inequality incorrectly

Trap Explanation:

PITFALL

Sorting end ascending looks natural but breaks coverage detection for intervals with equal starts.

Interviewer Note:

CONTEXT

Checks if candidate knows the critical sorting order for coverage detection.

Master "Remove Covered Intervals" in Intervals

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More Intervals Quizzes

Consider this buggy code snippet for removing covered intervals:

Step 1: Analyze sorting key

Step 2: Understand coverage detection logic

Final Answer:

Quick Check:

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