Look for these signals in the problem:
- "Range sum/min/max query" with updates: Segment tree handles both in .
- "Count elements" in range satisfying condition: Segment tree with custom aggregation function.
- "Update range, query point": Lazy propagation variant handles range updates.
- "Merge sort based" counting: Segment tree on value space counts inversions, smaller numbers, etc.
- Dynamic order statistics: Segment tree tracks count of elements for rank queries.