You have [[3,6],[1,4],[8,10],[2,5]] and you need to find every overlapping pair.
No sorting. No tricks. Just raw comparisons.
With 4 intervals that means 6 pair checks. With 100 intervals? 4,950. With 1,000? Nearly half a million.
Can you even find them all without missing one?
Find the overlapping pairs. Tap two intervals to check.