Practice · 1 of 3

Lucky Receipts

CHALLENGE

Difficulty: advanced+25 XP

**Problem.** Line 1: n S. Line 2: n integers (may be negative). Print the number of contiguous subarrays whose sum is exactly S. **Constraints:** 1 <= n <= 200000; |a[i]|, |S| <= 1e9. Two-pointer shrinking is the classic near-miss here.

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