Which modification to the optimal approach is necessary to handle this variant correctly?
hard🎤 Interviewer Follow-up Q15 of Q15
Intervals - Insert Interval
Suppose the intervals list can contain overlapping intervals initially (not guaranteed sorted or disjoint), and you want to insert a new interval and return the merged list. Which modification to the optimal approach is necessary to handle this variant correctly?
AInsert the new interval in the correct position without sorting, then merge only intervals overlapping with the new interval.
BAppend the new interval, then sort and merge all intervals including the original overlapping ones.
CSkip sorting and merge intervals only if they overlap with the new interval to improve efficiency.
DUse a balanced tree data structure to insert and merge intervals dynamically without sorting.
Step-by-Step Solution
Solution:
Step 1: Understand initial intervals may overlap
Since intervals are not guaranteed sorted or disjoint, merging must consider all intervals, not just those overlapping newInterval.
Step 2: Modify approach to handle all overlaps
Appending newInterval and sorting all intervals ensures correct order, then merging all intervals handles existing overlaps and new overlaps caused by insertion.
Step 3: Why other options fail
Options B and C assume partial merging which misses existing overlaps; D is overcomplicated and not required.
Final Answer:
Option B -> Option B
Quick Check:
Sorting and merging all intervals handles arbitrary overlaps [OK]
Quick Trick:Sort and merge all intervals when initial list may overlap [OK]
Common Mistakes:
MISTAKES
Assuming initial intervals are sorted and disjoint
Trying partial merges only around new interval
Skipping sorting leads to incorrect merges
Trap Explanation:
PITFALL
Option B looks efficient but misses existing overlaps; only full sort+merge works reliably.
Interviewer Note:
CONTEXT
Tests if candidate can adapt solution to relaxed constraints and understand full merging necessity.
Master "Insert Interval" in Intervals
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