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The following code attempts to find the minimum number of arrows to burst balloons. Identify the bug that causes incorrect arrow count in some cases.

medium🐞 Bug Identification Q14 of Q15
Intervals - Minimum Number of Arrows to Burst Balloons
The following code attempts to find the minimum number of arrows to burst balloons. Identify the bug that causes incorrect arrow count in some cases.
ALine 6: Shooting arrow at start coordinate instead of end coordinate
BLine 4: Sorting by end coordinate is incorrect
CLine 2: Missing check for empty input
DLine 8: Using start > arrow_pos instead of start >= arrow_pos
Step-by-Step Solution

  1. Step 1: Analyze arrow shooting position

    Arrow should be shot at the end coordinate of the first balloon to cover maximum overlaps.

  2. Step 2: Identify impact of shooting at start

    Shooting at start may miss balloons overlapping at the end, causing extra arrows.

  3. Final Answer:

    Option A -> Option A

  4. Quick Check:

    Correct arrow position is critical for minimal arrow count [OK]
Quick Trick: Arrow must be at end coordinate, not start [OK]
Common Mistakes:
MISTAKES
  • Confusing start and end coordinates for arrow position
  • Using >= instead of > causing overcount
  • Ignoring empty input edge case
Trap Explanation:
PITFALL
  • Shooting at start looks plausible but breaks coverage on overlapping intervals.
Interviewer Note:
CONTEXT
  • Checks if candidate can spot subtle off-by-one or coordinate misuse bugs.
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