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Consider the following Python code that determines if a person can attend all meetings given a list of intervals. What is the return value when the input is [[7,10],[2,4]]?

easy🧾 Code Trace Q12 of Q15
Intervals - Meeting Rooms I
Consider the following Python code that determines if a person can attend all meetings given a list of intervals. What is the return value when the input is [[7,10],[2,4]]?
from typing import List

def can_attend_meetings(intervals: List[List[int]]) -> bool:
    intervals.sort(key=lambda x: x[0])
    end = float('-inf')
    for interval in intervals:
        if interval[0] < end:
            return False
        end = interval[1]
    return True

print(can_attend_meetings([[7,10],[2,4]]))
ANone
BFalse
CRaises an exception
DTrue
Step-by-Step Solution
  1. Step 1: Sort intervals by start time

    Input [[7,10],[2,4]] becomes [[2,4],[7,10]].
  2. Step 2: Iterate and check overlaps

    Initialize end = -inf. First interval start=2 > -inf, update end=4. Second interval start=7 > 4, update end=10. No overlaps found, return True.
  3. Final Answer:

    Option D -> Option D
  4. Quick Check:

    Intervals sorted and no overlaps detected [OK]
Quick Trick: Sort then check if current start < previous end [OK]
Common Mistakes:
MISTAKES
  • Confusing return value due to unsorted intervals
Trap Explanation:
PITFALL
  • Not sorting intervals first leads to incorrect overlap detection and wrong return value.
Interviewer Note:
CONTEXT
  • Tests ability to mentally execute code and understand sorting impact on logic.
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