Practice · 2 of 5
Twice As Small
CHALLENGE
Difficulty: advanced+25 XP
**Bài toán.** Count the pairs i < j with a[i] > 2·a[j]. **Constraints:** 1 ≤ n ≤ 200000; |a[i]| ≤ 10^9. **Output:** one integer (64-bit).
Press Submit to check your solution.
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